Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 07, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Entity Registrant Name	Diamondback Energy, Inc.
Entity Central Index Key	0001539838
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		98,167,289
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 7,801,460,276

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 112,446	$ 1,666,574
Restricted cash	0	500
Accounts receivable:
Joint interest and other	73,038	49,476
Oil and natural gas sales	158,575	70,349
Related party	0	297
Inventories	9,108	1,983
Derivative instruments	531	0
Prepaid expenses and other	4,903	2,987
Total current assets	358,601	1,792,166
Property and equipment:
Oil and natural gas properties, full cost method of accounting ($4,105,865 and $1,730,519 excluded from amortization at December 31, 2017 and 2016, respectively)	9,232,694	5,160,261
Midstream assets	191,519	8,362
Other property, equipment and land	80,776	58,290
Accumulated depletion, depreciation, amortization and impairment	(2,161,372)	(1,836,056)
Net property and equipment	7,343,617	3,390,857
Funds held in escrow	6,304	121,391
Derivative instruments	0	709
Other assets	62,463	44,557
Total assets	7,770,985	5,349,680
Current liabilities:
Accounts payable-trade	94,590	47,648
Accounts payable-related party	0	1
Accrued capital expenditures	221,256	60,350
Other accrued liabilities	92,512	55,330
Revenues and royalties payable	68,703	23,405
Derivative instruments	100,367	22,608
Total current liabilities	577,428	209,342
Long-term debt	1,477,347	1,105,912
Derivative instruments	6,303	0
Asset retirement obligations	20,122	16,134
Deferred income taxes	108,048	0
Total liabilities	2,189,248	1,331,388
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized, 98,167,289 issued and outstanding at December 31, 2017; 90,143,934 issued and outstanding at December 31, 2016	982	901
Additional paid-in capital	5,291,011	4,215,955
Accumulated deficit	(37,133)	(519,394)
Total Diamondback Energy, Inc. stockholders’ equity	5,254,860	3,697,462
Non-controlling interest	326,877	320,830
Total equity	5,581,737	4,018,292
Total liabilities and equity	$ 7,770,985	$ 5,349,680

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Oil and natural gas properties, full cost method of accounting amount excluded from amortization	$ 4,105,865	$ 1,730,519
Common Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares, Authorized	200,000,000	100,000,000
Common Stock, Shares, Issued	98,167,289	90,143,934
Common Stock, Shares, Outstanding	98,167,289	90,143,934

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Oil sales	$ 1,044,017	$ 470,528	$ 405,715
Natural gas sales	52,210	22,506	19,592
Natural gas liquid sales	90,048	34,073	21,426
Lease bonus	11,764	0	0
Midstream services	7,072	0	0
Total revenues	1,205,111	527,107	446,733
Costs and expenses:
Lease operating expenses	126,524	82,428	82,625
Production and ad valorem taxes	73,505	34,456	32,990
Gathering and transportation	12,834	11,606	6,091
Midstream services	10,409	0	0
Depreciation, depletion and amortization	326,759	178,015	217,697
Impairment of oil and natural gas properties	0	245,536	814,798
General and administrative expenses (including non-cash equity-based compensation, net of capitalized amounts, of $25,537, $26,453 and $18,529 for the year ended December 31, 2017, 2016 and 2015, respectively)	48,669	42,619	31,968
Asset retirement obligation accretion	1,391	1,064	833
Total costs and expenses	600,091	595,724	1,187,002
Income (loss) from operations	605,020	(68,617)	(740,269)
Other income (expense):
Interest expense, net	(40,554)	(40,684)	(41,510)
Other income, net	10,235	3,064	728
Gain (loss) on derivative instruments, net	(77,512)	(25,345)	31,951
Loss on extinguishment of debt	0	(33,134)	0
Total other expense, net	(107,831)	(96,099)	(8,831)
Income (loss) before income taxes	497,189	(164,716)	(749,100)
Provision for (benefit from) income taxes	(19,568)	192	(201,310)
Net income (loss)	516,757	(164,908)	(547,790)
Net income attributable to non-controlling interest	34,496	126	2,838
Net income (loss) attributable to Diamondback Energy, Inc.	$ 482,261	$ (165,034)	$ (550,628)
Earnings per common share:
Basic (in dollars per share)	$ 4.95	$ (2.20)	$ (8.74)
Diluted (in dollars per share)	$ 4.94	$ (2.20)	$ (8.74)
Weighted average common shares outstanding:
Basic (in shares)	97,458	75,077	63,019
Diluted (in shares)	97,688	75,077	63,019

Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Noncontrolling Interest [Member]
Balance at beginning of period at Dec. 31, 2014	$ 1,985,213	$ 569	$ 1,554,174	$ 196,268	$ 234,202
Balance at beginning of period, shares at Dec. 31, 2014		56,888,000
Increase (Decrease) in Stockholders' Equity
Unit-based compensation	3,929	$ 0	0	0	3,929
Distribution to non-controlling interest	(7,968)	0	0	0	(7,968)
Stock-based compensation	20,645	$ 0	20,645	0	0
Common shares issued in public offering, net of offering costs, shares		9,488,000
Common shares issued in public offering, net of offering costs	650,073	$ 94	649,979	0	0
Exercise of stock options and awards of restricted stock	4,871	$ 5	4,866	0	0
Exercise of stock options and awards of restricted stock, shares		421,000
Net income (loss)	(547,790)	$ 0	0	(550,628)	2,838
Balance at end of period at Dec. 31, 2015	2,108,973	$ 668	2,229,664	(354,360)	233,001
Balance at end of period, shares at Dec. 31, 2015		66,797,000
Increase (Decrease) in Stockholders' Equity
Net proceeds from issuance of common units - Viper Energy Partners LP	93,462	$ 0	0	0	93,462
Unit-based compensation	3,815	0	0	0	3,815
Distribution to non-controlling interest	(9,574)	0	0	0	(9,574)
Stock-based compensation	29,717	$ 0	29,717	0	0
Common shares issued in public offering, net of offering costs, shares		23,000,000
Common shares issued in public offering, net of offering costs	1,956,308	$ 229	1,956,079	0	0
Exercise of stock options and awards of restricted stock	499	$ 4	495	0	0
Exercise of stock options and awards of restricted stock, shares		347,000
Net income (loss)	(164,908)	$ 0	0	(165,034)	126
Balance at end of period at Dec. 31, 2016	$ 4,018,292	$ 901	4,215,955	(519,394)	320,830
Balance at end of period, shares at Dec. 31, 2016	90,143,934	90,144,000
Increase (Decrease) in Stockholders' Equity
Net proceeds from issuance of common units - Viper Energy Partners LP	$ 369,896	$ 0	0	0	369,896
Unit-based compensation	2,395	0	0	0	2,395
Common units issued for acquisition	3,050	0	0	0	3,050
Distribution to non-controlling interest	(41,367)	0	0	0	(41,367)
Stock-based compensation	31,783	0	31,783	0	0
Common shares issued in public offering, net of offering costs	14	$ 0	14	0	0
Common shares issued for acquisition, shares		7,685,918
Common shares issued for acquisition	809,173	$ 77	809,096	0	0
Exercise of stock options and awards of restricted stock	359	$ 4	355	0	0
Exercise of stock options and awards of restricted stock, shares		337,000
Change in ownership of consolidated subsidiaries, net	(128,615)	$ 0	233,808	0	(362,423)
Net income (loss)	516,757	0	0	482,261	34,496
Balance at end of period at Dec. 31, 2017	$ 5,581,737	$ 982	$ 5,291,011	$ (37,133)	$ 326,877
Balance at end of period, shares at Dec. 31, 2017	98,167,289	98,167,000

Consolidated Statements of Cash Flows - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ 516,757	$ (164,908)	$ (547,790)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Provision for deferred income taxes	(20,567)	0	(201,545)
Impairment of oil and natural gas properties	0	245,536	814,798
Asset retirement obligation accretion	1,391	1,064	833
Depreciation, depletion and amortization	326,759	178,015	217,697
Amortization of debt issuance costs	3,943	2,717	2,601
Loss on early extinguishment of debt	0	33,134	0
Change in fair value of derivative instruments	84,240	26,522	112,918
Income from equity investment	(657)	(676)	0
Equity-based compensation expense	25,537	26,453	18,529
Gain (loss) on sale of assets, net	(455)	(61)	668
Changes in operating assets and liabilities:
Accounts receivable	(97,611)	(35,030)	8,998
Accounts receivable-related party	297	1,294	2,149
Restricted cash	500	0	0
Inventories	(2,245)	(255)	224
Prepaid expenses and other	(11,362)	(709)	(1,310)
Accounts payable and accrued liabilities	36,762	15,922	802
Accounts payable and accrued liabilities-related party	(2)	(216)	218
Income tax payable	814	0	0
Accrued interest	(20,774)	(3,161)	(255)
Revenues and royalties payable	45,298	6,439	(13,034)
Net cash provided by operating activities	888,625	332,080	416,501
Cash flows from investing activities:
Additions to oil and natural gas properties	(792,599)	(362,450)	(419,241)
Additions to oil and natural gas properties-related party	0	(637)	(271)
Additions to midstream assets	(68,139)	(1,188)	0
Purchase of other property, equipment and land	(22,779)	(9,891)	(1,213)
Acquisition of leasehold interests	(1,960,591)	(611,280)	(437,455)
Acquisition of mineral interests	(407,450)	(205,721)	(43,907)
Acquisition of midstream assets	(50,279)	0	0
Proceeds from sale of assets	65,656	4,661	9,739
Funds held in escrow	104,087	(121,391)	0
Equity investments	(188)	(2,345)	(2,702)
Net cash used in investing activities	(3,132,282)	(1,310,242)	(895,050)
Cash flows from financing activities:
Proceeds from borrowings under credit facility	753,500	164,000	425,001
Repayment under credit facility	(383,500)	(89,000)	(603,001)
Proceeds from senior notes	0	1,000,000	0
Repayment of senior notes	0	(450,000)	0
Premium on extinguishment of debt	0	(26,561)	0
Debt issuance costs	(9,296)	(15,063)	(526)
Public offering costs	(510)	(1,182)	(586)
Proceeds from public offerings	370,344	2,051,503	650,688
Proceeds from exercise of stock options	358	498	4,873
Distributions to non-controlling interest	(41,367)	(9,574)	(7,968)
Net cash provided by financing activities	689,529	2,624,621	468,481
Net increase (decrease) in cash and cash equivalents	(1,554,128)	1,646,459	(10,068)
Cash and cash equivalents at beginning of period	1,666,574	20,115	30,183
Cash and cash equivalents at end of period	112,446	1,666,574	20,115
Supplemental disclosure of cash flow information:
Interest paid, net of capitalized interest	57,668	38,177	38,758
Cash paid for income taxes	0	192	267
Supplemental disclosure of non-cash transactions:
Change in accrued capital expenditures	160,906	413	(69,460)
Capitalized stock-based compensation	$ 8,641	$ 7,079	$ 6,043
Common stock issued for oil and natural gas properties	809,173	0	0
Asset retirement obligations acquired	$ 2,432	$ 3,696	$ 3,159

Description of the Business and Basis of Presentation	12 Months Ended
Description of the Business and Basis of Presentation	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business and Basis of Presentation	DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION Organization and Description of the Business Diamondback Energy, Inc. (“Diamondback” or the “Company”) is an independent oil and gas company focused on the acquisition, development, exploration and exploitation of unconventional, onshore oil and natural gas reserves in the Permian Basin in West Texas. Diamondback was incorporated in Delaware on December 30, 2011. On June 17, 2014, Diamondback entered into a contribution agreement with Viper Energy Partners LP (the “Partnership”), Viper Energy Partners GP LLC (the “General Partner”) and Viper Energy Partners LLC to transfer Diamondback’s ownership interest in Viper Energy Partners LLC to the Partnership in exchange for 70,450,000 common units. Diamondback also owns and controls the General Partner, which holds a non-economic general partner interest in the Partnership. On June 23, 2014, the Partnership completed its initial public offering (the “Viper Offering”) of 5,750,000 common units, and the Company’s common units represented an approximate 92% limited partner interest in the Partnership. On September 19, 2014, the Partnership completed an underwritten public offering of 3,500,000 common units. At the completion of this offering, the Company owned approximately 88% of the common units of the Partnership. See Note 4–Viper Energy Partners LP for additional information regarding the Partnership. The wholly-owned subsidiaries of Diamondback, as of December 31, 2017, include Diamondback E&P LLC, a Delaware limited liability company, Diamondback O&G LLC, a Delaware limited liability company, Viper Energy Partners GP LLC, a Delaware limited liability company, and Rattler Midstream LLC (formerly known as White Fang Energy LLC), a Delaware limited liability company. The consolidated subsidiaries include the wholly-owned subsidiaries as well as Viper Energy Partners LP, a Delaware limited partnership, and Viper Energy Partners LLC, a Delaware limited liability company. Basis of Presentation The consolidated financial statements include the accounts of the Company and its subsidiaries after all significant intercompany balances and transactions have been eliminated upon consolidation. The Partnership is consolidated in the financial statements of the Company. As of December 31, 2017, the Company owned approximately 64% of the common units of the Partnership and the Company’s wholly owned subsidiary, Viper Energy Partners GP LLC, is the General Partner of the Partnership.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates

Certain amounts included in or affecting the Company’s consolidated financial statements and related disclosures must be estimated by management, requiring certain assumptions to be made with respect to values or conditions that cannot be known with certainty at the time the consolidated financial statements are prepared. These estimates and assumptions affect the amounts the Company reports for assets and liabilities and the Company’s disclosure of contingent assets and liabilities at the date of the consolidated financial statements. Actual results could differ from those estimates.

The Company evaluates these estimates on an ongoing basis, using historical experience, consultation with experts and other methods the Company considers reasonable in the particular circumstances. Nevertheless, actual results may differ significantly from the Company’s estimates. Any effects on the Company’s business, financial position or results of operations resulting from revisions to these estimates are recorded in the period in which the facts that give rise to the revision become known. Significant items subject to such estimates and assumptions include, but are not limited to, estimates of proved oil and natural gas reserves and related present value estimates of future net cash flows therefrom, the carrying value of oil and natural gas properties, asset retirement obligations, the fair value determination of acquired assets and liabilities, equity-based compensation, fair value estimates of commodity derivatives and estimates of income taxes.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with a maturity of three months or less and money market funds to be cash equivalents. The Company maintains cash and cash equivalents in bank deposit accounts which, at times, may exceed the federally insured limits. The Company has not experienced any significant losses from such investments.

Restricted Cash

In 2014, a subsidiary of the Company entered into an agreement to purchase certain overriding royalty interests and deposited $0.5 million in escrow. The subsidiary subsequently terminated the agreement and requested a return of the deposit. The seller challenged the termination and the escrow agent tendered the deposit to the court subject to a judicial determination of the proper payment of the funds. The parties reached a settlement of this matter in April 2017 and the funds were distributed in accordance with the terms of the settlement. Pending such distribution, these funds were classified as restricted cash.

Accounts Receivable

Accounts receivable consist of receivables from joint interest owners on properties the Company operates and from sales of oil and natural gas production delivered to purchasers. The purchasers remit payment for production directly to the Company. Most payments for production are received within three months after the production date.

Accounts receivable are stated at amounts due from joint interest owners or purchasers, net of an allowance for doubtful accounts when the Company believes collection is doubtful. For receivables from joint interest owners, the Company typically has the ability to withhold future revenue disbursements to recover any non-payment of joint interest billings. Accounts receivable outstanding longer than the contractual payment terms are considered past due. The Company determines its allowance by considering a number of factors, including the length of time accounts receivable are past due, the Company’s previous loss history, the debtor’s current ability to pay its obligation to the Company, the condition of the general economy and the industry as a whole. The Company writes off specific accounts receivable when they become uncollectible, and payments subsequently received on such receivables are credited to the allowance for doubtful accounts. No allowance was deemed necessary at December 31, 2017 or December 31, 2016.

Derivative Instruments

The Company is required to recognize its derivative instruments on the consolidated balance sheets as assets or liabilities at fair value with such amounts classified as current or long-term based on their anticipated settlement dates. The accounting for the changes in fair value of a derivative depends on the intended use of the derivative and resulting designation. The Company has not designated its derivative instruments as hedges for accounting purposes and, as a result, marks its derivative instruments to fair value and recognizes the cash and non-cash change in fair value on derivative instruments for each period in the consolidated statements of operations.

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash and cash equivalents, restricted cash, receivables, payables, derivatives and senior notes. The carrying amount of cash and cash equivalents, receivables and payables approximates fair value because of the short-term nature of the instruments. The fair value of the revolving credit facility approximates its carrying value based on the borrowing rates currently available to the Company for bank loans with similar terms and maturities. The fair value of the senior notes are determined using quoted market prices. Derivatives are recorded at fair value (see Note 14–Fair Value Measurements).

Oil and Natural Gas Properties

The Company uses the full cost method of accounting for its oil and natural gas properties. Under this method, all acquisition, exploration and development costs, including certain internal costs, are capitalized and amortized on a composite unit of production method based on proved oil, natural gas liquids and natural gas reserves. Internal costs capitalized to the full cost pool represent management’s estimate of costs incurred directly related to exploration and development activities such as geological and other administrative costs associated with overseeing the exploration and development activities. Costs, including related employee costs, associated with production and operation of the properties are charged to expense as incurred. All other internal costs not directly associated with exploration and development activities are charged to expense as they are incurred. Sales of oil and natural gas properties, whether or not being amortized currently, are accounted for as adjustments of capitalized costs, with no gain or loss recognized, unless such adjustments would significantly alter the relationship between capitalized costs and proved reserves of oil, natural gas liquids and natural gas. Any income from services provided by subsidiaries to working interest owners of properties in which the Company also owns an interest, to the extent they exceed related costs incurred, are accounted for as reductions of capitalized costs of oil and natural gas properties proportionate to the Company’s investment in the subsidiary (see Note 7–Equity Method Investments). Depletion of evaluated oil and natural gas properties is computed on the units of production method, whereby capitalized costs plus estimated future development costs are amortized over total proved reserves. The average depletion rate per barrel equivalent unit of production was $11.11, $11.23 and $17.84 for the years ended December 31, 2017, 2016 and 2015, respectively. Depreciation, depletion and amortization expense for oil and natural gas properties was $321.9 million, $176.4 million and $216.1 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Under this method of accounting, the Company is required to perform a ceiling test each quarter. The test determines a limit, or ceiling, on the book value of the proved oil and natural gas properties. Net capitalized costs are limited to the lower of unamortized cost net of deferred income taxes, or the cost center ceiling. The cost center ceiling is defined as the sum of (a) estimated future net revenues, discounted at 10% per annum, from proved reserves, based on the trailing 12-month unweighted average of the first-day-of-the-month price, adjusted for any contract provisions, and excluding the estimated abandonment costs for properties with asset retirement obligations recorded on the balance sheet, (b) the cost of properties not being amortized, if any, and (c) the lower of cost or market value of unproved properties included in the cost being amortized, including related deferred taxes for differences between the book and tax basis of the oil and natural gas properties. If the net book value, including related deferred taxes, exceeds the ceiling, an impairment or non-cash writedown is required. During the years ended December 31, 2016 and 2015, the Company recorded impairments on proved oil and natural gas properties of $245.5 million and $814.8 million, respectively. No impairment on proved oil and natural gas properties was recorded for the year ended December 31, 2017.

Costs associated with unevaluated properties are excluded from the full cost pool until the Company has made a determination as to the existence of proved reserves. The Company assesses all items classified as unevaluated property on an annual basis for possible impairment. The Company assesses properties on an individual basis or as a group if properties are individually insignificant. The assessment includes consideration of the following factors, among others: intent to drill; remaining lease term; geological and geophysical evaluations; drilling results and activity; the assignment of proved reserves; and the economic viability of development if proved reserves are assigned. During any period in which these factors indicate an impairment, the cumulative drilling costs incurred to date for such property and all or a portion of the associated leasehold costs are transferred to the full cost pool and are then subject to amortization.

Other Property, Equipment and Land

Other property and equipment is recorded at cost. The Company expenses maintenance and repairs in the period incurred. Upon retirements or disposition of assets, the cost and related accumulated depreciation are removed from the consolidated balance sheet with the resulting gains or losses, if any, reflected in operations. Depreciation of other property and equipment is computed using the straight line method over their estimated useful lives, which range from three to fifteen years. Depreciation expense for other property and equipment was $1.4 million for each of the years ended December 31, 2017, 2016 and 2015.

Asset Retirement Obligations

The Company measures the future cost to retire its tangible long-lived assets and recognizes such cost as a liability for legal obligations associated with the retirement of long-lived assets that result from the acquisition, construction or normal operation of a long-lived asset.

The Company records a liability relating to the retirement and removal of all assets used in their businesses. Asset retirement obligations represent the future abandonment costs of tangible assets, namely wells. The fair value of a liability for an asset’s retirement obligation is recorded in the period in which it is incurred if a reasonable estimate of fair value can be made and the corresponding cost is capitalized as part of the carrying amount of the related long-lived asset. The liability is accreted to its then present value each period, and the capitalized cost is depreciated over the useful life of the related asset. If the liability is settled for an amount other than the recorded amount or if there is a change in the estimated liability, the difference is recorded in oil and natural gas properties.

Impairment of Long-Lived Assets

Other property and equipment used in operations are reviewed whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss is recognized only if the carrying amount of a long-lived asset is not recoverable from its estimated future undiscounted cash flows. An impairment loss is the difference between the carrying amount and fair value of the asset. The Company had no such impairment losses for the years ended December 31, 2017, 2016 and 2015, respectively.

Capitalized Interest

The Company capitalizes interest on expenditures made in connection with exploration and development projects that are not subject to current amortization. Interest is capitalized only for the period that activities are in progress to bring these projects to their intended use. Capitalized interest cannot exceed gross interest expense. The Company capitalized interest of $22.1 million for the year ended December 31, 2017. The Company did not have any capitalized interest for the years ended December 31, 2016 and 2015.

Inventories

Inventories are stated at the lower of cost or market and consist of tubular goods and equipment at December 31, 2017 and 2016. The Company’s tubular goods and equipment are primarily comprised of oil and natural gas drilling or repair items such as tubing, casing and pumping units. The inventory is primarily acquired for use in future drilling or repair operations and is carried at lower of cost or market. “Market”, in the context of inventory valuation, represents net realizable value, which is the amount that the Company is allowed to bill to the joint accounts under joint operating agreements to which the Company is a party. As of December 31, 2017, the Company estimated that all of its tubular goods and equipment will be utilized within one year.

Debt Issuance Costs

Other assets included capitalized costs related to the credit facility of $16.7 million and $8.2 million, net of accumulated amortization of $7.0 million and $4.9 million, as of December 31, 2017 and 2016, respectively. Long-term debt included capitalized costs related to the senior notes of $15.2 million and $14.8 million, net of accumulated amortization of $2.0 million and $0.2 million, as of December 31, 2017 and 2016, respectively. The costs associated with the senior notes are being netted against the senior notes balances and are being amortized over the term of the senior notes using the effective interest method. The costs associated with the Company’s credit facility that are included in other assets are being amortized over the term of the facility.

Other Accrued Liabilities

Other accrued liabilities consist of the following:



	December 31,
	2017		2016
	(In thousands)
Liability for drilling costs prepaid by joint interest partners	$	30,320	$	21,595
Interest payable	6,770		5,445
Lease operating expenses payable	27,850		13,857
Ad valorem taxes payable	3,306		776
Current portion of asset retirement obligations	1,163		1,288
Other	23,103		12,369
Total other accrued liabilities	$	92,512	$	55,330

Revenue and Royalties Payable

For certain oil and natural gas properties, where the Company serves as operator, the Company receives production proceeds from the purchaser and further distributes such amounts to other revenue and royalty owners. Production proceeds that the Company has not yet distributed to other revenue and royalty owners are reflected as revenue and royalties payable in the accompanying consolidated balance sheets. The Company recognizes revenue for only its net revenue interest in oil and natural gas properties.

Revenue Recognition

Oil and natural gas revenues are recorded when title passes to the purchaser, net of royalty interests, discounts and allowances, as applicable. The Company accounts for oil and natural gas production imbalances using the sales method, whereby a liability is recorded when the Company’s overtake volumes exceed its estimated remaining recoverable reserves. No receivables are recorded for those wells where the Company has taken less than its ownership share of production. The Company did not have any gas imbalances as of December 31, 2017 or December 31, 2016. Revenues from oil and natural gas services are recognized when services are provided.

Investments

Equity investments in which the Company exercises significant influence but does not control are accounted for using the equity method. Under the equity method, generally the Company’s share of investees’ earnings or loss is recognized in the statement of operations. The Company reviews its investments to determine if a loss in value which is other than a temporary decline has occurred. If such loss has occurred, the Company would recognize an impairment provision. There was no impairment for the Company’s equity investments for the years ended December 31, 2017, 2016 and 2015.

For additional information on the Company’s investments, see Note 7–Equity Method Investments.

Accounting for Equity-Based Compensation

The Company grants various types of stock-based awards including stock options and restricted stock units. The Partnership grants various unit-based awards including unit options and phantom units to employees, officers and directors of the General Partner and the Company who perform services for the Partnership. These plans and related accounting policies are defined and described more fully in Note 10–Equity-Based Compensation. Equity compensation awards are measured at fair value on the date of grant and are expensed, net of estimated forfeitures, over the required service period.

Concentrations

The Company is subject to risk resulting from the concentration of its crude oil and natural gas sales and receivables with several significant purchasers. For the year ended December 31, 2017, three purchasers each accounted for more than 10% of the Company’s revenue: Shell Trading (US) Company (31%); Koch Supply & Trading LP (19%); and Enterprise Crude Oil LLC (11%). For the year ended December 31, 2016, three purchasers each accounted for more than 10% of the Company’s revenue: Shell Trading (US) Company (45%); Koch Supply & Trading LP (15%); and Enterprise Crude Oil LLC (13%). For the year ended December 31, 2015, two purchasers each accounted for more than 10% of the Company’s revenue: Shell Trading (US) Company (59%); and Enterprise Crude Oil LLC (15%). The Company does not require collateral and does not believe the loss of any single purchaser would materially impact its operating results, as crude oil and natural gas are fungible products with well-established markets and numerous purchasers.

Environmental Compliance and Remediation

Environmental compliance and remediation costs, including ongoing maintenance and monitoring, are expensed as incurred. Liabilities are accrued when environmental assessments and remediation are probable, and the costs can be reasonably estimated.

Income Taxes

Diamondback uses the asset and liability method of accounting for income taxes, under which deferred tax assets and liabilities are recognized for the future tax consequences of (i) temporary differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and (ii) operating loss and tax credit carryforwards. Deferred income tax assets and liabilities are based on enacted tax rates applicable to the future period when those temporary differences are expected to be recovered or settled. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period the rate change is enacted. A valuation allowance is provided for deferred tax assets when it is more likely than not the deferred tax assets will not be realized.

The Company is subject to margin tax in the state of Texas. During the years ended December 31, 2017, 2016 and 2015, the Company had no margin tax expense. The Company’s 2013, 2014, 2015, 2016 and 2017 federal income tax and state margin tax returns remain open to examination by tax authorities. As of December 31, 2017 and December 31, 2016, the Company had no unrecognized tax benefits that would have a material impact on the effective tax rate. The Company is continuing its practice of recognizing interest and penalties related to income tax matters as interest expense and general and administrative expenses, respectively. During the years ended December 31, 2017, 2016 and 2015, there was no interest or penalties associated with uncertain tax positions recognized in the Company’s consolidated financial statements.

Recent Accounting Pronouncements

Recently Issued Pronouncements

In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update 2014-09, “Revenue from Contracts with Customers”. This update supersedes most of the existing revenue recognition requirements in GAAP and requires (i) an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services and (ii) requires expanded disclosures regarding the nature, amount, timing and certainty of revenue and cash flows from contracts with customers.

The Company will adopt this Accounting Standards Update effective January 1, 2018 using the modified retrospective approach. The Company has reviewed various contracts that represent its material revenue streams and determined that there will be no impact to its financial position, results of operations or liquidity. Upon adoption of this Accounting Standards Update, the Company will not be required to record a cumulative effect adjustment due to the new Accounting Standards Update not having a quantitative impact compared to existing GAAP. Also, upon adoption of this Accounting Standards Update, the Company will not be required to alter its existing information technology and internal controls outside of ongoing contract review processes in order to identify impacts of future revenue contracts entered into by the Company. The Company does not anticipate the disclosure requirements under the Accounting Standards Update to have a material change on how it presents information regarding its revenue streams as compared to existing GAAP.

In January 2016, the Financial Accounting Standards Board issued Accounting Standards Update 2016-01, “Financial Instruments–Overall”. This update applies to any entity that holds financial assets or owes financial liabilities. This update requires equity investments (except for those accounted for under the equity method or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The Partnership will adopt this standard effective January 1, 2018 by means of a cumulative-effect adjustment which will decrease Unitholders’ Equity and will bring the fair value of its investment to $15.2 million or $15.20 per unit for that investment.

In August 2016, the Financial Accounting Standards Board issued Accounting Standards Update 2016-15, “Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments”. This update apples to all entities that are required to present a statement of cash flows. This update provides guidance on eight specific cash flow issues: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies; including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company will adopt this update effective January 1, 2018 using the retrospective transition method. Adoption of this standard will change the presentation of its cash flows and did not have a material impact on its consolidated financial statements.

In November 2016, the Financial Accounting Standards Board issued Accounting Standards Update 2016-18, “Statement of Cash Flows - Restricted Cash”. This update affects entities that have restricted cash or restricted cash equivalents. The Company will adopt this update retrospectively effective January 1, 2018. Adoption of this standard will change the presentation of its cash flows and did not have a material impact on its consolidated financial statements.

In January 2017, the Financial Accounting Standards Board issued Accounting Standards Update 2017-01, “Business Combinations - Clarifying the Definition of a Business”. This update apples to all entities that must determine whether they acquired or sold a business. This update provides a screen to determine when a set is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The Company will adopt this update prospectively effective January 1, 2018. The adoption of this update will not have an impact on its financial position, results of operations or liquidity.

Accounting Pronouncements Not Yet Adopted

In February 2016, the Financial Accounting Standards Board issued Accounting Standards Update 2016-02, “Leases”. This update applies to any entity that enters into a lease, with some specified scope exemptions. Under this update, a lessee should recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. While there were no major changes to the lessor accounting, changes were made to align key aspects with the revenue recognition guidance. This update will be effective for public entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. Entities will be required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company believes the primary impact of adopting this standard will be the recognition of assets and liabilities on the balance sheet for current operating leases. The Company is still evaluating the impact of this standard.

In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update 2016-13, “Financial Instruments - Credit Losses”. This update affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off-balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. This update will be effective for financial statements issued for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. This update will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company does not believe the adoption of this standard will have a material impact on the Company’s consolidated financial statements since the Company does not have a history of credit losses.

Acquisitions

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Acquisitions

ACQUISITIONS

2017 Activity

On February 28, 2017, the Company completed its acquisition of certain oil and natural gas properties, midstream assets and other related assets in the Delaware Basin for an aggregate purchase price consisting of $1.74 billion in cash and 7.69 million shares of the Company’s common stock, of which approximately 1.15 million shares were placed in an indemnity escrow. This transaction included the acquisition of (i) approximately 100,306 gross (80,339 net) acres primarily in Pecos and Reeves counties for approximately $2.5 billion and (ii) midstream assets for approximately $47.6 million. The Company used the net proceeds from its December 2016 equity offering, net proceeds from its December 2016 debt offering, cash on hand and other financing sources to fund the cash portion of the purchase price for this acquisition.

The following represents the fair value of the assets and liabilities assumed on the acquisition date. The aggregate consideration transferred was $2.5 billion, resulting in no goodwill or bargain purchase gain.



	(in thousands)
Proved oil and natural gas properties	$	386,308
Unevaluated oil and natural gas properties	2,122,597
Midstream assets	47,432
Prepaid capital costs	3,460
Oil inventory	839
Equipment	163
Revenues and royalties payable	(9,650		)
Asset retirement obligations	(1,550		)
Total fair value of net assets	$	2,549,599

The Company has included in its consolidated statements of operations revenues of $81.4 million and direct operating expenses of $23.5 million for the period from February 28, 2017 to December 31, 2017 due to the acquisition.

Pro Forma Financial Information

The following unaudited summary pro forma consolidated statement of operations data of Diamondback for the year ended December 31, 2017 and 2016 have been prepared to give effect to the February 28, 2017 acquisition as if it had occurred on January 1, 2016. The pro forma data are not necessarily indicative of the financial results that would have been attained had the acquisitions occurred on January 1, 2016.

The pro forma data also necessarily exclude various operation expenses related to the properties and the financial statements should not be viewed as indicative of operations in future periods.



	Year Ended December 31,
	2017		2016
	(in thousands, except per share amounts)
Revenues	$	1,228,040	$	627,301
Income (loss) from operations	619,369		(12,812		)
Net income (loss)	472,649		(109,229		)
Basic earnings per common share	4.85		(1.45		)
Diluted earnings per common share	4.84		(1.45		)

2016 Activity

On September 1, 2016, the Company acquired from an unrelated third party leasehold interests and related assets in the Southern Delaware Basin for an aggregate purchase price of $558.5 million. This transaction included approximately 26,797 gross (19,262 net) acres primarily in Reeves and Ward counties. The Company financed this acquisition with net proceeds from the July 2016 equity offering discussed in Note 9 and cash on hand.

2015 Activity

During 2015, the Company completed acquisitions from unrelated third party sellers of an aggregate of approximately 16,940 gross (12,672 net) acres in the Midland Basin, primarily in northwest Howard County, for an aggregate purchase price of approximately $437.5 million. The acquisitions were accounted for according to the acquisition method, which requires the recording of net assets acquired and consideration transferred at fair value. These acquisitions were funded with the net proceeds of the May 2015 equity offering discussed in Note 9–Capital Stock and Earnings Per Share and borrowings under the Company’s revolving credit facility discussed in Note 8–Debt.

On July 9, 2015, the Company completed the sale of an approximate average 1.5% overriding royalty interest in certain of its acreage primarily located in Howard County, Texas to the Partnership for $31.1 million. The Partnership primarily funded this acquisition with borrowings under its revolving credit facility discussed in Note 8 – Debt.

Property and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment

PROPERTY AND EQUIPMENT

Property and equipment includes the following:



	December 31,
	2017			2016
	(in thousands)
Oil and natural gas properties:
Subject to depletion	$	5,126,829		$	3,429,742
Not subject to depletion	4,105,865			1,730,519
Gross oil and natural gas properties	9,232,694			5,160,261
Accumulated depletion	(1,009,893		)	(687,685		)
Accumulated impairment	(1,143,498		)	(1,143,498		)
Oil and natural gas properties, net	7,079,303			3,329,078
Midstream assets	191,519			8,362
Other property, equipment and land	80,776			58,290
Accumulated depreciation	(7,981		)	(4,873		)
Property and equipment, net of accumulated depreciation, depletion, amortization and impairment	$	7,343,617		$	3,390,857

Balance of costs not subject to depletion:
Incurred in 2017	$	2,746,936
Incurred in 2016	727,411
Incurred in 2015	301,879
Incurred in 2014	316,455
Incurred in 2013	13,184
Total not subject to depletion	$	4,105,865

The Company uses the full cost method of accounting for its oil and natural gas properties. Under this method, all acquisition, exploration and development costs, including certain internal costs, are capitalized and amortized on a composite unit of production method based on proved oil, natural gas liquids and natural gas reserves. Internal costs capitalized to the full cost pool represent management’s estimate of costs incurred directly related to exploration and development activities such as geological and other administrative costs associated with overseeing the exploration and development activities. Costs, including related employee costs, associated with production and operation of the properties are charged to expense as incurred. All other internal costs not directly associated with exploration and development activities are charged to expense as they are incurred. Capitalized internal costs were approximately $22.0 million $17.2 million and $15.2 million for the years ended December 31, 2017, 2016 and 2015, respectively. Costs associated with unevaluated properties are excluded from the full cost pool until the Company has made a determination as to the existence of proved reserves. The inclusion of the Company’s unevaluated costs into the amortization base is expected to be completed within three to five years. Acquisition costs not currently being amortized are primarily related to unproved acreage that the Company plans to prove up through drilling. The Company has no plans to let any acreage expire. Sales of oil and natural gas properties, whether or not being amortized currently, are accounted for as adjustments of capitalized costs, with no gain or loss recognized, unless such adjustments would significantly alter the relationship between capitalized costs and proved reserves of oil, natural gas liquids and natural gas.

As a result of the significant decline in prices during 2016, the Company recorded non-cash ceiling test impairments for the years ended December 31, 2016 and 2015 of $245.5 million and $814.8 million, respectively, which are included in accumulated depletion. No impairment on proved oil and natural gas properties was recorded for the year ended December 31, 2017. For 2016 and 2015, the impairment charges affected the Company’s reported net income but did not reduce its cash flow. In addition to commodity prices, the Company’s production rates, levels of proved reserves, future development costs, transfers of unevaluated properties and other factors will determine its actual ceiling test calculation and impairment analysis in future periods.

At December 31, 2017, there was $26.0 million in exploration costs and development costs and $22.1 million in capitalized interest that are not subject to depletion. At December 31, 2016, there were no exploration costs, development costs or capitalized interest that are not subject to depletion.

Viper Energy Partners LP	12 Months Ended
Viper Energy Partners LP	Dec. 31, 2017
Noncontrolling Interest [Abstract]
Viper Energy Partners LP	VIPER ENERGY PARTNERS LP The Partnership is a publicly traded Delaware limited partnership, the common units of which are listed on the Nasdaq Global Market under the symbol “VNOM”. The Partnership was formed by Diamondback on February 27, 2014, to, among other things, own, acquire and exploit oil and natural gas properties in North America. The Partnership is currently focused on oil and natural gas properties in the Permian Basin. Viper Energy Partners GP LLC, a consolidated subsidiary of Diamondback, serves as the general partner of, and holds a non-economic general partner interest in, the Partnership. As of December 31, 2017, the Company owned approximately 64% of the common units of the Partnership. Prior to the completion on June 23, 2014 of the Viper Offering, Diamondback owned all of the general and limited partner interests in the Partnership. The Viper Offering consisted of 5,750,000 common units representing approximately 8% of the limited partner interests in the Partnership at a price to the public of $26.00 per common unit. In connection with the Viper Offering, Diamondback contributed all of the membership interests in Viper Energy Partners LLC to the Partnership in exchange for 70,450,000 common units. The contribution of Viper Energy Partners LLC to the Partnership was accounted for as a combination of entities under common control with assets and liabilities transferred at their carrying amounts in a manner similar to a pooling of interests. During the year ended December 31, 2017, the Partnership distributed $89.5 million to Diamondback in respect of its common units. In August 2016, the Partnership completed an underwritten public offering of 8,050,000 common units, which included 1,050,000 common units issued pursuant to an option to purchase additional common units granted to the underwriter. In this offering, Diamondback purchased 2,000,000 common units from the underwriter at $15.60 per unit, which is the price per common unit paid by the underwriter to the Partnership. Following the August 2016 public offering, Diamondback had an approximate 83% limited partner interest in the Partnership. The Partnership received net proceeds from this offering of approximately $125.0 million, after deducting underwriting discounts and commissions and estimated offering expenses, which it used to fund an acquisition and repaid outstanding borrowings under its revolving credit facility. In January 2017, the Partnership completed an underwritten public offering of 9,775,000 common units, which included 1,275,000 common units issued pursuant to an option to purchase additional common units granted to the underwriters. The Partnership received net proceeds from this offering of approximately $147.5 million, after deducting underwriting discounts and commissions and estimated offering expenses, of which the Partnership used $120.5 million to repay the outstanding borrowings under its revolving credit agreement and the balance was used for general partnership purposes, which included additional acquisitions. In July 2017, the Partnership completed an underwritten public offering of 16,100,000 common units, which included 2,100,000 common units issued pursuant to an option to purchase additional common units granted to the underwriters. In this offering, we purchased 700,000 common units, an affiliate of the General Partner purchased 3,000,000 common units and certain officers and directors of the Company and the General Partner purchased an aggregate of 114,000 common units, in each case directly from the underwriters. Following this offering, the Company had an approximate 64% limited partner interest in the Partnership. The Partnership received net proceeds from this offering of approximately $232.5 million, after deducting underwriting discounts and commissions and estimated offering expenses, of which the Partnership used $152.8 million to repay all of the then-outstanding borrowings under the Partnership’s revolving credit facility and the balance was used fund a portion of the purchase price for acquisitions and for general partnership purposes. As a result of these public offerings and the Partnership’s issuance of unit-based compensation, the Company’s ownership percentage in the Partnership was reduced. During the year ended December 31, 2017, the Company recorded a $362.4 million decrease to Non-controlling interest in the Partnership with an increase to Additional paid-in capital, which represents the difference between the Company’s share of the underlying net book value in the Partnership before and after the respective Partnership common unit transactions, on the Company’s consolidated balance sheet. Partnership Agreement In connection with the closing of the Viper Offering, the General Partner and Diamondback entered into the first amended and restated agreement of limited partnership, dated as of June 23, 2014 (the “Partnership Agreement”). The Partnership Agreement requires the Partnership to reimburse the General Partner for all direct and indirect expenses incurred or paid on the Partnership’s behalf and all other expenses allocable to the Partnership or otherwise incurred by the General Partner in connection with operating the Partnership’s business. The Partnership Agreement does not set a limit on the amount of expenses for which the General Partner and its affiliates may be reimbursed. These expenses include salary, bonus, incentive compensation and other amounts paid to persons who perform services for the Partnership or on its behalf and expenses allocated to the General Partner by its affiliates. The General Partner is entitled to determine the expenses that are allocable to the Partnership. Tax Sharing In connection with the closing of the Viper Offering, the Partnership entered into a tax sharing agreement with Diamondback, dated June 23, 2014, pursuant to which the Partnership agreed to reimburse Diamondback for its share of state and local income and other taxes for which the Partnership’s results are included in a consolidated tax return filed by Diamondback with respect to taxable periods including or beginning on June 23, 2014. The amount of any such reimbursement is limited to the tax the Partnership would have paid had it not been included in a combined group with Diamondback. Diamondback may use its tax attributes to cause its consolidated group, of which the Partnership may be a member for this purpose, to owe less or no tax. In such a situation, the Partnership agreed to reimburse Diamondback for the tax the Partnership would have owed had the tax attributes not been available or used for the Partnership’s benefit, even though Diamondback had no cash tax expense for that period. Other Agreements See Note 11–Related Party Transactions for information regarding the advisory services agreement the Partnership and the General Partner entered into with Wexford Capital LP (“Wexford”). The Partnership has entered into a secured revolving credit facility with Wells Fargo Bank, National Association, (“Wells Fargo”) as administrative agent sole book runner and lead arranger. See Note 8–Debt for a description of this credit facility.

Asset Retirement Obligations

12 Months Ended

Dec. 31, 2017

Asset Retirement Obligation [Abstract]

Asset Retirement Obligations

ASSET RETIREMENT OBLIGATIONS

The following table describes the changes to the Company’s asset retirement obligations liability for the following periods:



	Year Ended December 31,
	2017			2016			2015
	(in thousands)
Asset retirement obligations, beginning of period	$	17,422		$	12,711		$	8,486
Additional liabilities incurred	1,526			637			594
Liabilities acquired	2,432			3,696			3,159
Liabilities settled	(1,555		)	(711		)	(292		)
Accretion expense	1,391			1,064			833
Revisions in estimated liabilities	69			25			(69		)
Asset retirement obligations, end of period	21,285			17,422			12,711
Less current portion	1,163			1,288			193
Asset retirement obligations - long-term	$	20,122		$	16,134		$	12,518

The Company’s asset retirement obligations primarily relate to the future plugging and abandonment of wells and related facilities. The Company estimates the future plugging and abandonment costs of wells, the ultimate productive life of the properties, a risk-adjusted discount rate and an inflation factor in order to determine the current present value of this obligation. To the extent future revisions to these assumptions impact the present value of the existing asset retirement obligation liability, a corresponding adjustment is made to the oil and natural gas property balance.

Equity Method Investments	12 Months Ended
Equity Method Investments	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	EQUITY METHOD INVESTMENTS In October 2014, the Company obtained a 25% interest in HMW Fluid Management LLC, which was formed to develop, own and operate an integrated water management system to gather, store, process, treat, distribute and dispose of water to exploration and production companies operating in Midland, Martin and Andrews Counties, Texas. The board of this entity may also authorize the entity to offer these services to other counties in the Permian Basin and to pursue other business opportunities. During the year ended December 31, 2017, the Company invested $0.2 million in this entity and recorded income of $0.7 million, which was the Company’s share of HMW Fluid Management LLC’s net income, bringing the Company’s total investment to $7.2 million at December 31, 2017. During the year ended December 31, 2016, the Company invested $2.3 million in this entity and recorded income of $0.7 million, which was the Company’s share of HMW Fluid Management LLC’s net income, bringing its total investment to $6.3 million at December 31, 2016. The Company will retain a minority interest after all commitments are received. The entity was formed as a limited liability company and maintains a specific ownership account for each investor, similar to a partnership capital account structure. The Company accounts for this investment under the equity method of accounting.

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

DEBT

Long-term debt consisted of the following as of the dates indicated:



	December 31,
	2017			2016
	(in thousands)
4.750 % Senior Notes due 2024	500,000			500,000
5.375 % Senior Notes due 2025	500,000			500,000
Unamortized debt issuance costs	(13,153		)	(14,588		)
Revolving credit facility	397,000			—
Partnership revolving credit facility	93,500			120,500
Total long-term debt	$	1,477,347		$	1,105,912

2024 Senior Notes

On October 28, 2016, the Company issued $500.0 million in aggregate principal amount of 4.750% Senior Notes due 2024 (the “2024 Senior Notes”). The 2024 Senior Notes bear interest at a rate of 4.750% per annum, payable semi-annually, in arrears on May 1 and November 1 of each year, commencing on May 1, 2017 and will mature on November 1, 2024. All of the Company’s existing and future restricted subsidiaries that guarantee its revolving credit facility or certain other debt guarantee the 2024 Senior Notes, provided, however, that the 2024 Senior Notes are not guaranteed by the Partnership, the General Partner, Viper Energy Partners LLC or Rattler Midstream LLC, and will not be guaranteed by any of the Company’s future unrestricted subsidiaries. See also “Note 16. Subsequent Events–New Senior Notes due 2025 and Repayment of Portion of Outstanding Borrowings under Revolving Credit Facility.”

The 2024 Senior Notes were issued under, and are governed by, an indenture among the Company, the subsidiary guarantors party thereto and Wells Fargo, as the trustee, as supplemented (the “2024 Indenture”). The 2024 Indenture contains certain covenants that, subject to certain exceptions and qualifications, among other things, limit the Company’s ability and the ability of the restricted subsidiaries to incur or guarantee additional indebtedness, make certain investments, declare or pay dividends or make other distributions on capital stock, prepay subordinated indebtedness, sell assets including capital stock of restricted subsidiaries, agree to payment restrictions affecting the Company’s restricted subsidiaries, consolidate, merge, sell or otherwise dispose of all or substantially all of its assets, enter into transactions with affiliates, incur liens, engage in business other than the oil and natural gas business and designate certain of the Company’s subsidiaries as unrestricted subsidiaries.

The Company may on any one or more occasions redeem some or all of the 2024 Senior Notes at any time on or after November 1, 2019 at the redemption prices (expressed as percentages of principal amount) of 103.563% for the 12-month period beginning on November 1, 2019, 102.375% for the 12-month period beginning on November 1, 2020, 101.188% for the 12-month period beginning on November 1, 2021 and 100.000% beginning on November 1, 2022 and at any time thereafter with any accrued and unpaid interest to, but not including, the date of redemption. Prior to November 1, 2019, the Company may on any one or more occasions redeem all or a portion of the 2024 Senior Notes at a price equal to 100% of the principal amount of the 2024 Senior Notes plus a “make-whole” premium and accrued and unpaid interest to the redemption date. In addition, any time prior to November 1, 2019, the Company may on any one or more occasions redeem the 2024 Senior Notes in an aggregate principal amount not to exceed 35% of the aggregate principal amount of the 2024 Senior Notes issued prior to such date at a redemption price of 104.750%, plus accrued and unpaid interest to the redemption date, with an amount equal to the net cash proceeds from certain equity offerings.

2025 Senior Notes

On December 20, 2016, the Company issued $500.0 million in aggregate principal amount of 5.375% Senior Notes due 2025 (the “2025 Senior Notes”). The 2025 Senior Notes bear interest at a rate of 5.375% per annum, payable semi-annually, in arrears on May 31 and November 30 of each year, commencing on May 31, 2017 and will mature on May 31, 2025. All of the Company’s existing and future restricted subsidiaries that guarantee its revolving credit facility or certain other debt guarantee the 2025 Senior Notes, provided, however, that the 2025 Senior Notes are not guaranteed by the Partnership, the General Partner, Viper Energy Partners LLC or Rattler Midstream LLC, and will not be guaranteed by any of the Company’s future unrestricted subsidiaries.

The 2025 Senior Notes were issued under an indenture, dated as of December 20, 2016, among the Company, the guarantors party thereto and Wells Fargo Bank, as the trustee (the “2025 Indenture”). The 2025 Indenture contains certain covenants that, subject to certain exceptions and qualifications, among other things, limit the Company’s ability and the ability of the restricted subsidiaries to incur or guarantee additional indebtedness, make certain investments, declare or pay dividends or make other distributions on capital stock, prepay subordinated indebtedness, sell assets including capital stock of restricted subsidiaries, agree to payment restrictions affecting the Company’s restricted subsidiaries, consolidate, merge, sell or otherwise dispose of all or substantially all of its assets, enter into transactions with affiliates, incur liens, engage in business other than the oil and natural gas business and designate certain of the Company’s subsidiaries as unrestricted subsidiaries.

The Company may on any one or more occasions redeem some or all of the 2025 Senior Notes at any time on or after May 31, 2020 at the redemption prices (expressed as percentages of principal amount) of 104.031% for the 12-month period beginning on May 31, 2020, 102.688% for the 12-month period beginning on May 31, 2021, 101.344% for the 12-month period beginning on May 31, 2022 and 100.000% beginning on May 31, 2023 and at any time thereafter with any accrued and unpaid interest to, but not including, the date of redemption. Prior to May 31, 2020, the Company may on any one or more occasions redeem all or a portion of the 2025 Senior Notes at a price equal to 100% of the principal amount of the 2025 Senior Notes plus a “make-whole” premium and accrued and unpaid interest to the redemption date. In addition, any time prior to May 31, 2020, the Company may on any one or more occasions redeem the 2025 Senior Notes in an aggregate principal amount not to exceed 35% of the aggregate principal amount of the 2025 Senior Notes issued prior to such date at a redemption price of 105.375%, plus accrued and unpaid interest to the redemption date, with an amount equal to the net cash proceeds from certain equity offerings.

As required under the terms of the registration rights agreements relating to the 2024 Senior Notes and the 2025 Senior Notes, on April 26, 2017, the Company filed with the SEC a Registration Statement on Form S-4 (the “Registration Statement”) relating to the exchange offers of the 2024 Senior Notes and the 2025 Senior Notes for substantially identical notes registered under the Securities Act (the “Exchange Offers”). The Registration Statement was declared effective by the SEC on June 21, 2017 and the Exchange Offers closed on July 27, 2017, in which all of the privately placed 2024 Senior Notes and 2025 Senior Notes were exchanged for substantially identical notes in the same aggregate principal amount that were registered under the Securities Act.

The Company’s Credit Facility

The Company and Diamondback O&G LLC, as borrower, entered into the second amended and restated credit agreement, dated November 1, 2013, as amended on June 9, 2014, November 13, 2014, June 21, 2016, December 15, 2016 and November 28, 2017, with a syndicate of banks, including Wells Fargo, as administrative agent, and its affiliate Wells Fargo Securities, LLC, as sole book runner and lead arranger. The credit agreement provides for a revolving credit facility in the maximum credit amount of $5.0 billion, subject to a borrowing base based on the Company’s oil and natural gas reserves and other factors (the “borrowing base”). The borrowing base is scheduled to be redetermined, under certain circumstances, annually with an effective date of May 1st, and, under certain circumstances, semi-annually with effective dates of May 1st and November 1st. In addition, the Company may request up to two additional redeterminations of the borrowing base during any 12-month period. As of December 31, 2017, the borrowing base was set at $1.8 billion, the Company had elected a commitment amount of $1.0 billion and the Company had $397.0 million of outstanding borrowings under the revolving credit facility. See “Note 16. Subsequent Events-New Senior Notes due 2025 and Repayment of Portion of Outstanding Borrowings under Revolving Credit Facility.”

Diamondback O&G LLC is the borrower under the credit agreement. As of December 31, 2017, the credit agreement is guaranteed by the Company, Diamondback E&P LLC and Rattler Midstream LLC (formerly known as White Fang Energy LLC) and will also be guaranteed by any of the Company’s future subsidiaries that are classified as restricted subsidiaries under the credit agreement. The credit agreement is also secured by substantially all of the assets of the Company, Diamondback O&G LLC and the guarantors.

The outstanding borrowings under the credit agreement bear interest at a per annum rate elected by the Company that is equal to an alternate base rate (which is equal to the greatest of the prime rate, the Federal Funds effective rate plus 0.5%, and 3-month LIBOR plus 1.0%) or LIBOR, in each case plus the applicable margin. The applicable margin ranges from 0.25% to 1.25% in the case of the alternate base rate and from 1.25% to 2.25% in the case of LIBOR, each of which applicable margin rates is increased by 0.25% per annum if the total debt to EBITDAX ratio is greater than 3.0 to 1.0. The applicable margin depends on the amount of loans and letters of credit outstanding in relation to the commitment, which is defined as the least of the maximum credit amount, the borrowing base and the elected commitment amount. The Company is obligated to pay a quarterly commitment fee ranging from 0.375% to 0.500% per year on the unused portion of the commitment, which fee is also dependent on the amount of loans and letters of credit outstanding in relation to the commitment. Loan principal may be optionally repaid from time to time without premium or penalty (other than customary LIBOR breakage), and is required to be repaid (a) to the extent the loan amount exceeds the commitment or the borrowing base, whether due to a borrowing base redetermination or otherwise (in some cases subject to a cure period), (b) in an amount equal to the net cash proceeds from the sale of property when a borrowing base deficiency or event of default exists under the credit agreement and (c) at the maturity date of November 1, 2022.

The credit agreement contains various affirmative, negative and financial maintenance covenants. These covenants, among other things, limit additional indebtedness, additional liens, sales of assets, mergers and consolidations, dividends and distributions, transactions with affiliates and entering into certain swap agreements and require the maintenance of the financial ratios described below.



Financial Covenant	Required Ratio
Ratio of total debt to EBITDAX	Not greater than 3.0 to 1.0
Ratio of current assets to liabilities, as defined in the credit agreement	Not less than 1.0 to 1.0

The covenant prohibiting additional indebtedness, as amended in November 2017, allows for the issuance of unsecured debt in the form of senior or senior subordinated notes if no default would result from the incurrence of such debt after giving effect thereto and if, in connection with any such issuance, the borrowing base is reduced by 25% of the stated principal amount of each such issuance.

As of December 31, 2017 and 2016, the Company was in compliance with all financial covenants under its revolving credit facility, as then in effect. The lenders may accelerate all of the indebtedness under the Company’s revolving credit facility upon the occurrence and during the continuance of any event of default. The credit agreement contains customary events of default, including non-payment, breach of covenants, materially incorrect representations, cross-default, bankruptcy and change of control. There are no cure periods for events of default due to non-payment of principal and breaches of negative and financial covenants, but non-payment of interest and breaches of certain affirmative covenants are subject to customary cure periods.

The Partnership’s Credit Agreement

On July 8, 2014, the Partnership entered into a secured revolving credit agreement with Wells Fargo, as administrative agent, and Wells Fargo Securities, as sole book runner and lead arranger. The credit agreement, as amended, provides for a revolving credit facility in the maximum credit amount of $2.0 billion and a borrowing base based on our oil and natural gas reserves and other factors (the “borrowing base”) of $400.0 million, subject to scheduled semi-annual and other elective borrowing base redeterminations. The borrowing base is scheduled to be re-determined semi-annually with effective dates of May 1st and November 1st. In addition, Viper may request up to three additional redeterminations of the borrowing base during any 12-month period. As of December 31, 2017, the borrowing base was set at $400.0 million, and the Partnership had $93.5 million of outstanding borrowings and $306.5 million available for future borrowings under its revolving credit facility.

The outstanding borrowings under the credit agreement bear interest at a per annum rate elected by the Partnership that is equal to an alternate base rate (which is equal to the greatest of the prime rate, the Federal Funds effective rate plus 0.5% and 3-month LIBOR plus 1.0%) or LIBOR, in each case plus the applicable margin. The applicable margin ranges from 0.75% to 1.75% per annum in the case of the alternate base rate and from 1.75% to 2.75% per annum in the case of LIBOR, in each case depending on the amount of loans and letters of credit outstanding in relation to the commitment, which is defined as the lesser of the maximum credit amount and the borrowing base. The Partnership is obligated to pay a quarterly commitment fee ranging from 0.375% to 0.500% per year on the unused portion of the commitment, which fee is also dependent on the amount of loans and letters of credit outstanding in relation to the commitment. Loan principal may be optionally repaid from time to time without premium or penalty (other than customary LIBOR breakage), and is required to be repaid (i) to the extent the loan amount exceeds the commitment or the borrowing base, whether due to a borrowing base redetermination or otherwise (in some cases subject to a cure period), (ii) in an amount equal to the net cash proceeds from the sale of property when a borrowing base deficiency or event of default exists under the credit agreement and (iii) at the maturity date of November 1, 2022. The loan is secured by substantially all of the Partnership and its subsidiary’s assets.

The credit agreement contains various affirmative, negative and financial maintenance covenants. These covenants, among other things, limit additional indebtedness, purchases of margin stock, additional liens, sales of assets, mergers and consolidations, dividends and distributions, transactions with affiliates and entering into certain swap agreements and require the maintenance of the financial ratios described below.



Financial Covenant	Required Ratio
Ratio of total debt to EBITDAX	Not greater than 4.0 to 1.0
Ratio of current assets to liabilities, as defined in the credit agreement	Not less than 1.0 to 1.0

The covenant prohibiting additional indebtedness allows for the issuance of unsecured debt of up to $400.0 million in the form of senior unsecured notes and, in connection with any such issuance, the reduction of the borrowing base by 25% of the stated principal amount of each such issuance. A borrowing base reduction in connection with such issuance may require a portion of the outstanding principal of the loan to be repaid.

The lenders may accelerate all of the indebtedness under the Partnership’s credit agreement upon the occurrence and during the continuance of any event of default. The Partnership’s credit agreement contains customary events of default, including non-payment, breach of covenants, materially incorrect representations, cross-default, bankruptcy and change of control. There are no cure periods for events of default due to non-payment of principal and breaches of negative and financial covenants, but non-payment of interest and breaches of certain affirmative covenants are subject to customary cure periods.

Interest expense

The following amounts have been incurred and charged to interest expense for the years ended December 31, 2017, 2016 and 2015:



	Year Ended December 31,
	2017			2016		2015
	(in thousands)
Interest expense	$	60,671		$	39,642	$	40,221
Less capitalized interest	(22,097		)	—		—
Other fees and expenses	2,160			1,426		1,292
Total interest expense	$	40,734		$	41,068	$	41,513

Capital Stock and Earnings Per Share

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Capital Stock and Earnings Per Share

CAPITAL STOCK AND EARNINGS PER SHARE

Diamondback completed the following equity offerings during the years ended December 31, 2017, 2016 and 2015:



Date	Number of Shares of Common Stock Sold	Number of Shares of Common Stock Issued to Underwriters	Price per Share Sold to Underwriters		Proceeds Received by the Company
January 2015	2,012,500	262,500	$	59.34	$	119,422
May 2015	4,600,000	600,000	$	72.53	$	333,638
August 2015	2,875,000	375,000	$	68.74	$	197,628
January 2016	4,600,000	600,000	$	55.33	$	254,518
July 2016	6,325,000	825,000	$	87.24	$	551,777
December 2016	12,075,000	1,575,000	$	95.3025	$	1,150,828

Earnings Per Share

The Company’s basic earnings per share amounts have been computed based on the weighted-average number of shares of common stock outstanding for the period. Diluted earnings per share include the effect of potentially dilutive shares outstanding for the period. Additionally, for the diluted earnings per share computation, the per share earnings of the Partnership are included in the consolidated earnings per share computation based on the consolidated group’s holdings of the subsidiary.

A reconciliation of the components of basic and diluted earnings per common share is presented in the table below:



	Year Ended December 31,
	2017		2016			2015

Net income (loss) attributable to common stock	$	482,261	$	(165,034	)	$	(550,628	)
Weighted average common shares outstanding
Basic weighted average common units outstanding	97,458		75,077			63,019
Effect of dilutive securities:
Potential common shares issuable	230		—			—
Diluted weighted average common shares outstanding	97,688		75,077			63,019
Basic net income (loss) attributable to common stock	$	4.95	$	(2.20	)	$	(8.74	)
Diluted net income (loss) attributable to common stock	$	4.94	$	(2.20	)	$	(8.74	)

For the years ended December 31, 2017, 2016 and 2015, there were 45,690 shares, 243,654 shares and 100,924 shares, respectively, that were not included in the computation of diluted earnings per share because their inclusion would have been anti-dilutive for the periods presented but could potentially dilute basic earnings per share in future periods.

Equity-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock and Unit Based Compensation

EQUITY-BASED COMPENSATION

On October 10, 2012, the Board of Directors approved the Diamondback Energy, Inc. 2012 Equity Incentive Plan (the “2012 Plan”), which is intended to provide eligible employees with equity-based incentives. The 2012 Plan provides for the granting of incentive stock options, nonstatutory stock options, restricted awards (restricted stock and restricted stock units), performance awards, and stock appreciation rights, or any combination of the foregoing. A total of 2,500,000 shares of the Company’s common stock has been reserved for issuance pursuant to this plan.

The following table presents the effects of the equity and stock based compensation plans and related costs:



	2017		2016		2015
	(In thousands)
General and administrative expenses	$	25,537	$	26,453	$	18,529
Equity-based compensation capitalized pursuant to full cost method of accounting for oil and natural gas properties	8,641		7,079		6,043

On June 17, 2014, in connection with the Viper Offering, the Board of Directors of the General Partner adopted the Viper Energy Partners LP Long Term Incentive Plan (“Viper LTIP”), effective June 17, 2014, for employees, officers, consultants and directors of the General Partner and any of its affiliates, including Diamondback, who perform services for the Partnership. The Viper LTIP provides for the grant of unit options, unit appreciation rights, restricted units, unit awards, phantom units, distribution equivalent rights, cash awards, performance awards, other unit-based awards and substitute awards. A total of 9,070,356 common units has been reserved for issuance pursuant to the Viper LTIP. Common units that are cancelled, forfeited or withheld to satisfy exercise prices or tax withholding obligations will be available for delivery pursuant to other awards. The Viper LTIP is administered by the Board of Directors of the General Partner or a committee thereof.

Stock Options

In accordance with the 2012 Plan, the exercise price of stock options granted may not be less than the market value of the stock at the date of grant. The shares issued under the 2012 Plan will consist of new shares of Company stock. Unless otherwise specified in an agreement, options become exercisable ratably over a five-year period. However, as described above, options associated with the modification vest in four substantially equal annual installments and are exercisable for five years from the date of grant.

The fair value of the stock options on the date of grant is expensed over the applicable vesting period. The Company estimates the fair values of stock options granted using a Black-Scholes option valuation model, which requires the Company to make several assumptions. The Company does not have a long history of market prices, thus the expected volatility was determined using the historical volatility for a peer group of companies. The expected term of options granted was determined based on the contractual term of the awards and remaining vesting term at the modification date. The risk-free interest rate is based on the U.S. treasury yield curve rate for the expected term of the option at the date of grant. The Company does not anticipate paying cash dividends; therefore, the expected dividend yield was assumed to be zero. All such amounts represent the weighted-average amounts for each year.

The following table presents the Company’s stock option activity under the Company’s 2012 Equity Incentive Plan (“2012 Plan”) for the year ended December 31, 2017.



			Weighted Average
			Exercise		Remaining	Intrinsic
	Options		Price		Term	Value
					(in years)	(in thousands)
Outstanding at December 31, 2016	15,750		$	22.72
Exercised	(15,750	)	$	22.72
Outstanding at December 31, 2017	—		$	—	0.00	$	—

The aggregate intrinsic value of stock options that were exercised during the years ended December 31, 2016 and 2015 was $1.3 million and $15.7 million, respectively.

Restricted Stock Units

Under the 2012 Plan, approved by the Board of Directors, the Company is authorized to issue restricted stock and restricted stock units to eligible employees. The Company estimates the fair values of restricted stock awards and units as the closing price of the Company’s common stock on the grant date of the award, which is expensed over the applicable vesting period.

The following table presents the Company’s restricted stock units activity under the 2012 Plan during the year ended December 31, 2017.



	Restricted Stock Awards & Units		Weighted Average Grant-Date Fair Value
Unvested at December 31, 2016	206,004		$	70.33
Granted	188,438		$	102.77
Vested	(147,934	)	$	77.44
Forfeited	(2,931	)	$	89.21
Unvested at December 31, 2017	243,577		$	90.88

The aggregate fair value of restricted stock units that vested during the year ended December 31, 2017, 2016 and 2015 was $14.8 million, $12.5 million and $10.1 million, respectively. As of December 31, 2017, the Company’s unrecognized compensation cost related to unvested restricted stock awards and units was $14.4 million. Such cost is expected to be recognized over a weighted-average period of 1.5 years.

Performance-Based Restricted Stock Units

To provide long-term incentives for the executive officers to deliver competitive returns to the Company’s stockholders, the Company has granted performance-based restricted stock units to eligible employees. The ultimate number of shares awarded from these conditional restricted stock units is based upon measurement of total stockholder return of the Company’s common stock (“TSR”) as compared to a designated peer group during a three-year performance period.

In February 2015, eligible employees received performance restricted stock unit awards totaling 90,249 units from which a minimum of 0% and a maximum of 200% units could be awarded. The awards have a performance period of January 1, 2014 to December 31, 2016 and vested at December 31, 2016.

In February 2016, eligible employees received performance restricted stock unit awards totaling 174,325 units from which a minimum of 0% and a maximum of 200% units could be awarded. The awards have a performance period of January 1, 2016 to December 31, 2017 and vested at December 31, 2017. Eligible employees received additional performance restricted stock unit awards totaling 87,163 units from which a minimum of 0% and a maximum of 200% units could be awarded. The awards have a performance period of January 1, 2016 to December 31, 2018 and cliff vest at December 31, 2018.

In February 2017, eligible employees received performance restricted stock unit awards totaling 37,440 units from which a minimum of 0% and a maximum of 200% units could be awarded. The awards have a performance period of January 1, 2017 to December 31, 2018 and cliff vest at December 31, 2018. Eligible employees received additional performance restricted stock unit awards totaling 74,880 units from which a minimum of 0% and a maximum of 200% units could be awarded. The awards have a performance period of January 1, 2017 to December 31, 2019 and cliff vest at December 31, 2019.

The fair value of each performance restricted stock unit is estimated at the date of grant using a Monte Carlo simulation, which results in an expected percentage of units to be earned during the performance period. The following table presents a summary of the grant-date fair values of performance restricted stock units granted and the related assumptions.



	2017						2016
	Two-Year Performance Period			Three-Year Performance Period			Two-Year Performance Period			Three-Year Performance Period			2015
Grant-date fair value	$	162.13		$	168.73		$	103.41		$	102.35		$	137.14
Risk-free rate	1.27		%	1.59		%	0.86		%	1.10		%	0.49		%
Company volatility	39.32		%	41.14		%	41.91		%	42.16		%	43.36		%

The following table presents the Company’s performance restricted stock unit activity under the 2012 Plan for the year ended December 31, 2017.



	Performance Restricted Stock Units		Weighted Average Grant-Date Fair Value
Unvested at December 31, 2016	252,471		$	103.06
Granted	118,169		$	166.53
Vested	(168,314	)	$	103.41
Unvested at December 31, 2017⁽¹⁾	202,326		$	139.83


(1)	A maximum of 404,652 units could be awarded based upon the Company’s final TSR ranking.

As of December 31, 2017, the Company’s unrecognized compensation cost related to unvested performance based restricted stock awards and units was $15.6 million. Such cost is expected to be recognized over a weighted-average period of 1.4 years.

Partnership Unit Options

In accordance with the Viper LTIP, the exercise price of unit options granted may not be less than the market value of the common units at the date of grant. The units issued under the Viper LTIP will consist of new common units of the Partnership. On June 17, 2014, the Board of Directors of the General Partner granted 2,500,000 unit options to the executive officers of the General Partner. The unit options vest approximately 33% ratably on each of the first three anniversaries of the date of grant or earlier upon a change of control (as defined in the Viper LTIP). All outstanding unit options were amended effective November 29, 2016 to provide that vested unit options will become exercisable upon the earlier to occur of (i) the “Exercise Window Period” beginning on the third anniversary of the date of grant and ending on December 31, 2017, or (ii) the “Change of Control Exercise Period” beginning ten days before and ending on the date a change of control occurs (the earlier occurring of such events, the “Exercise Period”). At any time within the Exercise Period, if a participant attempts to exercise a vested unit option and the fair market value per unit as of such date is less than the exercise price per option unit, the vested unit option will not be exercisable. At the end of the Exercise Period, any vested unit option that is not exercisable or that has not been exercised will automatically terminate and become null and void.

The fair value of the unit options on the date of grant is expensed over the applicable vesting period. The Partnership estimates the fair values of unit options granted using a Black-Scholes option valuation model, which requires the Partnership to make several assumptions. At the time of grant the Partnership did not have a history of market prices, thus the expected volatility was determined using the historical volatility for a peer group of companies. The expected term of options granted was determined based on the contractual term of the awards. The risk-free interest rate is based on the U.S. treasury yield curve rate for the expected term of the unit option at the date of grant. The expected dividend yield was based upon projected performance of the Partnership.



	2015
Grant-date fair value	$	4.24
Expected volatility	36.0		%
Expected dividend yield	5.9		%
Expected term (in years)	3.0
Risk-free rate	0.99		%

The following table presents the unit option activity under the Viper LTIP for the year ended December 31, 2017.



			Weighted Average
	Unit Options		Exercise Price		Remaining Term	Intrinsic Value
					(in years)	(in thousands)
Outstanding at December 31, 2016	2,424,266		$	26.00
Forfeited	(2,416,666	)	$	26.00
Outstanding at December 31, 2017	7,600		$	18.49	0.00	$	—

Vested and Expected to vest at December 31, 2017	7,600		$	18.49	0.00	$	—

Phantom Units

Under the Viper LTIP, the Board of Directors of the General Partner is authorized to issue phantom units to eligible employees. The Partnership estimates the fair value of phantom units as the closing price of the Partnership’s common units on the grant date of the award, which is expensed over the applicable vesting period. Upon vesting the phantom units entitle the recipient one common unit of the Partnership for each phantom unit.

The following table presents the phantom unit activity under the Viper LTIP for the year ended December 31, 2017.



	Phantom Units		Weighted Average Grant-Date Fair Value
Unvested at December 31, 2016	21,048		$	16.23
Granted	116,567		$	17.09
Vested	(32,176	)	$	16.49
Unvested at December 31, 2017	105,439		$	17.10

The aggregate fair value of phantom units that vested during the year ended December 31, 2017 was $0.5 million. As of December 31, 2017, the unrecognized compensation cost related to unvested phantom units was $1.3 million. Such cost is expected to be recognized over a weighted-average period of 1.4 years.