Chord Energy (WLLBW) 10-K 27 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 20, 2020	Jun. 30, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-31899
Entity Registrant Name	WHITING PETROLEUM CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0098515
Entity Address, Address Line One	1700 Lincoln Street, Suite 4700
Entity Address, City or Town	Denver
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80203-4547
City Area Code	303
Local Phone Number	837-1661
Title of 12(b) Security	Common Stock
Trading Symbol	WLL
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		91,813,908
Entity Public Float			$ 1,693,000,000
Entity Central Index Key	0001255474
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 8,652	$ 13,607
Accounts receivable trade, net	308,249	294,468
Derivative assets	886	68,342
Prepaid expenses and other	13,196	22,009
Total current assets	330,983	398,426
Property and equipment:
Oil and gas properties, successful efforts method	12,812,007	12,195,659
Other property and equipment	178,689	134,212
Total property and equipment	12,990,696	12,329,871
Less accumulated depreciation, depletion and amortization	(5,735,239)	(5,003,509)
Total property and equipment, net	7,255,457	7,326,362
Other long-term assets	50,281	34,785
TOTAL ASSETS	7,636,721	7,759,573
Current liabilities:
Accounts payable trade	80,100	42,520
Revenues and royalties payable	202,010	228,284
Accrued capital expenditures	64,263	73,178
Accrued interest	53,928	55,080
Accrued lease operating expenses	38,262	37,499
Accrued liabilities and other	53,597	33,872
Taxes payable	26,844	31,357
Derivative liabilities	10,285
Accrued employee compensation and benefits	21,125	35,141
Total current liabilities	550,414	536,931
Long-term debt	2,799,885	2,792,321
Asset retirement obligations	131,208	131,544
Operating lease obligations	31,722
Deferred income taxes	73,593	1,373
Other long-term liabilities	24,928	27,088
Total liabilities	3,611,750	3,489,257
Commitments and contingencies
Equity:
Common stock, $0.001 par value, 225,000,000 shares authorized; 91,743,571 issued and 91,326,469 outstanding as of December 31, 2019 and 92,067,216 issued and 91,018,692 outstanding as of December 31, 2018	92	92
Additional paid-in capital	6,409,991	6,414,170
Accumulated deficit	(2,385,112)	(2,143,946)
Total equity	4,024,971	4,270,316
TOTAL LIABILITIES AND EQUITY	$ 7,636,721	$ 7,759,573

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED BALANCE SHEETS [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	91,743,571	92,067,216
Common stock, shares outstanding	91,326,469	91,018,692

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING REVENUES
Oil, NGL and natural gas sales	$ 1,572,245	$ 2,081,414	$ 1,481,435
Revenue from Contract with Customer, Product and Service [Extensible List]	us-gaap:OilAndGasMember	us-gaap:OilAndGasMember	us-gaap:OilAndGasMember
OPERATING EXPENSES
Lease operating expenses	$ 328,427	$ 311,895	$ 278,919
Transportation, gathering, compression and other	42,438	48,105	90,574
Production and ad valorem taxes	138,212	171,823	120,870
Depreciation, depletion and amortization	816,488	781,329	948,939
Exploration and impairment	54,738	67,368	936,177
General and administrative	132,609	123,250	124,288
Derivative loss, net	53,769	17,170	122,847
Loss on sale of properties	1,964	1,949	401,113
Amortization of deferred gain on sale	(9,069)	(11,354)	(12,963)
Total operating expenses	1,559,576	1,511,535	3,010,764
INCOME (LOSS) FROM OPERATIONS	12,669	569,879	(1,529,329)
OTHER INCOME (EXPENSE)
Interest expense	(191,047)	(197,474)	(191,088)
Gain (loss) on extinguishment of debt	7,830	(31,968)	(1,540)
Interest income and other	1,602	3,430	1,316
Total other expense	(181,615)	(226,012)	(191,312)
INCOME (LOSS) BEFORE INCOME TAXES	(168,946)	343,867	(1,720,641)
INCOME TAX EXPENSE (BENEFIT)
Current			(7,291)
Deferred	72,220	1,373	(475,688)
Total income tax expense (benefit)	72,220	1,373	(482,979)
NET INCOME (LOSS)	(241,166)	342,494	(1,237,662)
Net loss attributable to noncontrolling interests			14
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ (241,166)	$ 342,494	$ (1,237,648)
INCOME (LOSS) PER COMMON SHARE
Basic (in dollars per share)	$ (2.64)	$ 3.77	$ (13.65)
Diluted (in dollars per share)	$ (2.64)	$ 3.73	$ (13.65)
WEIGHTED AVERAGE SHARES OUTSTANDING
Basic (in shares)	91,285	90,953	90,683
Diluted (in shares)	91,285	91,869	90,683

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ (241,166)	$ 342,494	$ (1,237,662)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	816,488	781,329	948,939
Deferred income tax expense (benefit)	72,220	1,373	(475,688)
Amortization of debt issuance costs, debt discount and debt premium	28,340	30,700	31,715
Stock-based compensation	7,721	12,669	21,641
Amortization of deferred gain on sale	(9,069)	(11,354)	(12,963)
Loss on sale of properties	1,964	1,949	401,113
Oil and gas property impairments	17,866	45,288	899,853
(Gain) loss on extinguishment of debt	(7,830)	31,968	1,540
Non-cash derivative (gain) loss	78,626	(139,831)	131,129
Payment for settlement of commodity derivative contract		(61,036)
Other, net	(1,352)	(6,706)	(9,255)
Changes in current assets and liabilities:
Accounts receivable trade, net	(24,343)	(11,571)	(110,879)
Prepaid expenses and other	7,165	4,026	(444)
Accounts payable trade and accrued liabilities	40,117	11,368	(24,953)
Revenues and royalties payable	(26,274)	56,751	23,799
Taxes payable	(4,513)	2,586	(10,776)
Net cash provided by operating activities	755,960	1,092,003	577,109
CASH FLOWS FROM INVESTING ACTIVITIES
Drilling and development capital expenditures	(793,365)	(813,981)	(830,552)
Acquisition of oil and gas properties	(6,031)	(142,723)	(21,429)
Other property and equipment	(6,451)	(1,096)	(4,596)
Proceeds from sale of properties	72,000	4,746	929,974
Net cash provided by (used in) investing activities	(733,847)	(953,054)	73,397
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings under credit agreement	2,650,000	2,214,265	1,900,000
Repayments of borrowings under credit agreement	(2,275,000)	(2,214,265)	(2,450,000)
Issuance of 6.625% Senior Notes due 2026			1,000,000
Redemption of 6.5% Senior Subordinated Notes due 2018			(275,121)
Redemption of 5.0% Senior Notes due 2019		(990,023)
Repurchase of 1.25% Convertible Senior Notes due 2020	(297,000)
Repurchase of 5.75% Senior Notes due 2021	(95,279)
Debt issuance and extinguishment costs	(819)	(10,709)	(13,150)
Restricted stock used for tax withholdings	(3,830)	(4,744)	(6,081)
Proceeds from stock options exercised		755
Principal payments on finance lease obligations	(5,140)
Net cash provided by (used in) financing activities	(27,068)	(1,004,721)	155,648
NET CHANGE IN CASH AND CASH EQUIVALENTS	(4,955)	(865,772)	806,154
CASH AND CASH EQUIVALENTS
Beginning of period	13,607	879,379	73,225
End of period	8,652	13,607	879,379
SUPPLEMENTAL CASH FLOW DISCLOSURES
Income taxes paid (refunded), net	(7,508)	(32)	49
Interest paid, net of amounts capitalized	163,859	152,665	163,151
NONCASH INVESTING ACTIVITIES
Accrued capital expenditures and accounts payable related to property additions	86,088	$ 90,358	$ 80,762
Leasehold improvements paid for by third party lessor under office lease agreement	$ 10,422

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2015	Sep. 30, 2013	Sep. 30, 2010
6.625% Senior Notes due 2026 [Member]
Interest Rate (as a percent)	6.625%		6.625%
6.5% Senior Subordinated Notes due 2018 [Member]
Interest Rate (as a percent)			6.50%			6.50%
5.0% Senior Notes due 2019 [Member]
Interest Rate (as a percent)		5.00%			5.00%
1.25% Convertible Senior Notes due 2020 [Member]
Interest Rate (as a percent)	1.25%			1.25%
5.75% Senior Notes due 2021 [Member]
Interest Rate (as a percent)	5.75%

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total Whiting Shareholders' Equity [Member]	Noncontrolling Interest [Member]	Total
BALANCES at Dec. 31, 2016	$ 367	$ 6,389,435	$ (1,248,572)	$ 5,141,230	$ 7,962	$ 5,149,192
BALANCES (in shares) at Dec. 31, 2016	91,793
Increase (Decrease) in Shareholders' Equity
Net income/loss			(1,237,648)	(1,237,648)	(14)	(1,237,662)
Conveyance of third party ownership interest in Sustainable Water Resources, LLC					$ (7,948)	(7,948)
Reverse stock split	$ (276)	276
Restricted stock issued	$ 2	(2)
Restricted stock issued (in shares)	707
Restricted stock forfeited	$ (1)	1
Restricted stock forfeited (in shares)	(261)
Restricted stock used for tax withholdings		(6,081)		(6,081)		(6,081)
Restricted stock used for tax withholdings (in shares)	(144)
Stock-based compensation		21,641		21,641		21,641
Cumulative effect of change in accounting principle		220	(220)
BALANCES at Dec. 31, 2017	$ 92	6,405,490	(2,486,440)	3,919,142		3,919,142
BALANCES (in shares) at Dec. 31, 2017	92,095
Increase (Decrease) in Shareholders' Equity
Net income/loss			342,494	342,494		342,494
Exercise of stock options		755		755		755
Exercise of stock options (in shares)	16
Restricted stock issued (in shares)	451
Restricted stock forfeited (in shares)	(351)
Restricted stock used for tax withholdings		(4,744)		(4,744)		(4,744)
Restricted stock used for tax withholdings (in shares)	(144)
Stock-based compensation		12,669		12,669		12,669
BALANCES at Dec. 31, 2018	$ 92	6,414,170	(2,143,946)	4,270,316		4,270,316
BALANCES (in shares) at Dec. 31, 2018	92,067
Increase (Decrease) in Shareholders' Equity
Net income/loss			(241,166)	(241,166)		(241,166)
Adjustment to equity component of 2020 Convertible Senior Notes upon extinguishment		(8,070)		(8,070)		(8,070)
Restricted stock issued (in shares)	113
Restricted stock forfeited (in shares)	(286)
Restricted stock used for tax withholdings		(3,830)		(3,830)		(3,830)
Restricted stock used for tax withholdings (in shares)	(150)
Stock-based compensation		7,721		7,721		7,721
BALANCES at Dec. 31, 2019	$ 92	$ 6,409,991	$ (2,385,112)	$ 4,024,971		$ 4,024,971
BALANCES (in shares) at Dec. 31, 2019	91,744

CONSOLIDATED STATEMENTS OF EQ_2

CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical)	Nov. 08, 2017	Nov. 30, 2017
CONSOLIDATED STATEMENTS OF EQUITY [Abstract]
Reverse stock split ratio	0.25	0.25

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Operations Basis of Presentation of Consolidated Financial Statements Use of Estimates — Cash and Cash Equivalents Accounts Receivable Trade The Company routinely assesses the recoverability of all material trade and other receivables to determine their collectability. At December 31, 2019 and 2018, the Company had an allowance for doubtful accounts of $9 million and $12 million, respectively. Inventories — Oil and Gas Properties Proved. The Company assesses its proved oil and gas properties for impairment whenever events or circumstances indicate that the carrying value of the assets may not be recoverable. Such events include, but are not limited to, declines in commodity prices, increases in operating costs, unfavorable reserve revisions, poor well performance, changes in development plans and potential property divestitures. The impairment test compares undiscounted future net cash flows to the assets’ net book value. These undiscounted cash flows are driven by significant assumptions, including the Company’s expected future development activity, reserve estimates, forecasted pricing, future operating costs, capital expenditures and severance taxes. If the net capitalized costs exceed undiscounted future net cash flows, then the cost of the property is written down to fair value utilizing a discounted future net cash flow analysis. Impairment expense for proved properties totaled $835 million for the year ended December 31, 2017, which is reported in exploration and impairment expense. Net carrying values of retired, sold or abandoned properties that constitute less than a complete unit of depreciable property are charged or credited, net of proceeds, to accumulated depreciation, depletion and amortization unless doing so significantly affects the unit-of-production amortization rate, in which case a gain or loss is recognized in income. Gains or losses from the disposal of complete units of depreciable property are recognized to earnings. Unproved. Exploratory. Costs of drilling exploratory wells are initially capitalized, pending determination of whether the well has found proved reserves. If an exploratory well has not found proved reserves, the costs of drilling the well and other associated costs are charged to expense. Costs incurred for exploratory wells that find reserves, which cannot yet be classified as proved, continue to be capitalized if (i) the well has found a sufficient quantity of reserves to justify completion as a producing well and (ii) the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project. If either condition is not met, or if the Company obtains information that raises substantial doubt about the economic or operational viability of the project, the exploratory well costs, net of any salvage value, are expensed. Other Property and Equipment — buildings and leasehold improvements office equipment Debt Issuance Costs Debt Discounts and Premiums Derivative Instruments Derivatives and Hedging instruments. All derivative instruments, other than those that meet the “normal purchase normal sale” exclusion, are recorded on the balance sheet as either an asset or liability measured at fair value. Gains and losses from changes in the fair value of derivative instruments are recognized immediately in earnings, unless the derivative meets specific hedge accounting criteria and the derivative has been designated as a hedge. The Company does not currently apply hedge accounting to any of its outstanding derivative instruments, and as a result, all changes in derivative fair values are recognized currently in earnings. Cash flows from derivatives used to manage commodity price risk are classified in operating activities along with the cash flows of the underlying hedged transactions. The Company does not enter into derivative instruments for speculative or trading purposes. Refer to the “Derivative Financial Instruments” footnote for further information. Asset Retirement Obligations and Environmental Costs Asset Retirement and Environmental Obligations Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that obligations have been incurred and the amounts can be reasonably estimated. These liabilities are not reduced by possible recoveries from third parties. Deferred Gain on Sale Revenue Recognition Revenue from Contracts with Customers Taxes collected and remitted to governmental agencies on behalf of customers are not included in revenues or costs and expenses. General and Administrative Expenses Stock-based Compensation Expense 401(k) Plan Acquisition Costs — Maintenance and Repairs Income Taxes Earnings Per Share Industry Segment and Geographic Information Concentration of Credit Risk ​ ​ ​ ​ ​ Year Ended December 31, 2019 Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 12 % ​ ​ ​ ​ ​ Year Ended December 31, 2018 United Energy Trading, LLC ​ 17 % Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 11 % ​ ​ ​ ​ ​ Year Ended December 31, 2017 Tesoro Crude Oil Co 18 % ​ ​ ​ ​ ​ Commodity derivative contracts held by the Company are with nine counterparties, all of which are participants in Whiting’s credit facility and all of which have investment-grade ratings from Moody’s and Standard & Poor’s. As of December 31, 2019, outstanding derivative contracts with Capital One, N.A., JP Morgan Chase Bank, N.A., the Bank of Nova Scotia, Merrill Lynch Commodities, Inc. and Citibank, N.A. represented 28%, 16%, 14%, 13% and 11%, respectively, of total crude oil volumes hedged. Adopted and Recently Issued Accounting Pronouncements — Leases ASC Topic 842 – Leases

OIL AND GAS PROPERTIES

OIL AND GAS PROPERTIES	12 Months Ended
	Dec. 31, 2019
OIL AND GAS PROPERTIES [Abstract]
OIL AND GAS PROPERTIES	2. OIL AND GAS PROPERTIES Net capitalized costs related to the Company’s oil and gas producing activities at December 31, 2019 and 2018 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Costs of completed wells and facilities ​ $ 9,847,159 ​ $ 9,182,384 Proved leasehold costs ​ ​ 2,702,236 ​ ​ 2,729,593 Wells and facilities in progress ​ ​ 159,334 ​ ​ 160,995 Unproved leasehold costs ​ ​ 103,278 ​ ​ 122,687 Total oil and gas properties, successful efforts method ​ ​ 12,812,007 ​ ​ 12,195,659 Accumulated depletion ​ ​ (5,656,929) ​ ​ (4,937,579) Oil and gas properties, net ​ $ 7,155,078 ​ $ 7,258,080 ​

ACQUISITIONS AND DIVESTITURES

ACQUISITIONS AND DIVESTITURES	12 Months Ended
	Dec. 31, 2019
ACQUISITIONS AND DIVESTITURES [Abstract]
ACQUISITIONS AND DIVESTITURES	3. ACQUISITIONS AND DIVESTITURES 2019 Acquisitions and Divestitures On July 29, 2019, the Company completed the divestiture of its interests in 137 non-operated, producing oil and gas wells located in the McKenzie, Mountrail and Williams counties of North Dakota for aggregate sales proceeds of $27 million (before closing adjustments). On August 15, 2019, the Company completed the divestiture of its interests in 58 non-operated, producing oil and gas wells located in Richland County, Montana and Mountrail and Williams counties of North Dakota for aggregate sales proceeds of $26 million (before closing adjustments). There were no significant acquisitions during the year ended December 31, 2019. 2018 Acquisitions and Divestitures On July 31, 2018, the Company completed the acquisition of certain oil and gas properties located in Richland County, Montana and McKenzie County, North Dakota for an aggregate purchase price of $130 million (before closing adjustments). The properties consist of approximately 54,800 net acres in the Williston Basin, including interests in 117 producing oil and gas wells and undeveloped acreage. The revenue and earnings from these properties since the acquisition date are included in the Company’s consolidated financial statements for the year ended December 31, 2018 and are not material. Pro forma revenue and earnings for the acquired properties are not material to the Company’s consolidated financial statements and have not been presented accordingly. The acquisition was recorded using the acquisition method of accounting. The following table summarizes the allocation of the $123 million adjusted purchase price to the tangible assets acquired and liabilities assumed in this acquisition based on their relative fair values at the acquisition date, which did not result in the recognition of goodwill or a bargain purchase gain (in thousands): ​ ​ ​ ​ ​ Cash consideration ​ $ 122,861 ​ ​ ​ ​ Fair value of assets acquired: ​ ​ ​ Accounts receivable trade, net ​ $ 30 Prepaid expenses and other ​ ​ 43 Oil and gas properties, successful efforts method: ​ ​ ​ Proved oil and gas properties ​ ​ 106,860 Unproved oil and gas properties ​ ​ 21,769 Total fair value of assets acquired ​ ​ 128,702 ​ ​ ​ ​ Fair value of liabilities assumed: ​ ​ ​ Revenue and royalties payable ​ ​ 3,309 Asset retirement obligations ​ ​ 2,532 Total fair value of liabilities assumed ​ ​ 5,841 ​ ​ ​ ​ Total fair value of assets and liabilities acquired ​ $ 122,861 ​ 2017 Acquisitions and Divestitures On January 1, 2017, the Company completed the sale of its 50% interest in the Robinson Lake gas processing plant located in Mountrail County, North Dakota and its 50% interest in the Belfield gas processing plant located in Stark County, North Dakota, as well as the associated natural gas, crude oil and water gathering systems, effective January 1, 2017, for aggregate sales proceeds of $375 million (before closing adjustments). The Company used the net proceeds from this transaction to repay a portion of the debt outstanding under its credit agreement. On September 1, 2017, the Company completed the sale of its interests in certain producing oil and gas properties located in the Fort Berthold Indian Reservation area in Dunn and McLean counties of North Dakota, as well as other related assets and liabilities, (the “FBIR Assets”) for aggregate sales proceeds of $500 million (before closing adjustments). The sale was effective September 1, 2017 and resulted in a pre-tax loss on sale of $402 million. The Company used the net proceeds from the sale to repay a portion of the debt outstanding under its credit agreement. There were no significant acquisitions during the year ended December 31, 2017.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2019
LEASES [Abstract]
LEASES	4. LEASES The Company adopted ASC 842 effective January 1, 2019, which replaces previous lease accounting requirements under FASB ASC Topic 840 – Leases The Company has operating and finance leases for corporate and field offices, pipeline and midstream facilities and automobiles. Right-of-use (“ROU”) assets and liabilities associated with these leases are recognized at the lease commencement date based on the present value of the lease payments over the lease term. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments. Supplemental balance sheet information for the Company’s leases as of December 31, 2019 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Leases ​ Balance Sheet Classification ​ December 31, 2019 ​ ​ ​ ​ ​ ​ Operating Leases ​ ​ ​ ​ ​ Operating lease ROU assets ​ Other long-term assets ​ $ 31,882 Accumulated depreciation ​ Other long-term assets ​ ​ (4,895) Operating lease ROU assets, net ​ ​ ​ $ 26,987 ​ ​ ​ ​ ​ ​ Short-term operating lease obligations ​ Accrued liabilities and other ​ $ 7,346 Long-term operating lease obligations ​ Operating lease obligations ​ ​ 31,722 Total operating lease obligations ​ ​ ​ $ 39,068 ​ ​ ​ ​ ​ ​ Finance Leases ​ ​ ​ ​ ​ Finance lease ROU assets ​ Other property and equipment ​ $ 33,312 Accumulated depreciation ​ Accumulated depreciation, depletion and amortization ​ ​ (14,180) Finance lease ROU assets, net ​ ​ ​ $ 19,132 ​ ​ ​ ​ ​ ​ Short-term finance lease obligations ​ Accrued liabilities and other ​ $ 4,974 Long-term finance lease obligations ​ Other long-term liabilities ​ ​ 16,638 Total finance lease obligations ​ ​ ​ $ 21,612 ​ The Company’s leases have remaining terms of less than one year to 10 years. Most of the Company’s leases do not state or imply a discount rate. Accordingly, the Company uses its incremental borrowing rate based on information available at lease commencement to determine the present value of the lease payments. Information regarding the Company’s lease terms and discount rates as of December 31, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Remaining Lease Term ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 8 years Finance leases ​ ​ ​ ​ 5 years ​ ​ ​ ​ ​ ​ Weighted Average Discount Rate ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 4.6% Finance leases ​ ​ ​ ​ 8.6% ​ Operating lease cost is recognized on a straight-line basis over the lease term. Finance lease cost is recognized based on the effective interest method for the lease liability and straight-line amortization of the ROU asset, resulting in more cost being recognized in earlier lease periods. All payments for short-term leases, including leases with a term of one month or less, are recognized in income or capitalized to the cost of oil and gas properties on a straight-line basis over the lease term. Additionally, any variable payments, which are generally related to the corresponding utilization of the asset, are recognized in the period in which the obligation was incurred. Lease cost for the year ended December 31, 2019 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2019 Operating lease cost ​ $ 11,512 ​ ​ ​ ​ Finance lease cost: ​ ​ ​ Amortization of ROU assets ​ $ 5,661 Interest on lease liabilities ​ ​ 1,996 Total finance lease cost ​ $ 7,657 ​ ​ ​ ​ Short-term lease payments ​ $ 676,850 Variable lease payments ​ $ 31,812 ​ Total lease cost represents the total financial obligations of the Company, a portion of which has been or will be reimbursed by the Company’s working interest partners. Lease cost is included in various line items on the consolidated statements of operations or capitalized to oil and gas properties and is recorded at the Company’s net working interest. Supplemental cash flow information related to leases for the year ended December 31, 2019 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash flows from operating leases ​ $ 11,978 Operating cash flows from finance leases ​ $ 2,006 Financing cash flows from finance leases ​ $ 5,140 ​ ​ ​ ​ ROU assets obtained in exchange for new operating lease obligations ​ $ 18,658 ROU assets obtained in exchange for new finance lease obligations ​ $ 4,158 ​ The Company’s lease obligations as of December 31, 2019 will mature as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ending December 31, ​ Operating Leases ​ Finance Leases 2020 ​ $ 8,886 ​ $ 6,642 2021 ​ ​ 6,657 ​ ​ 5,753 2022 ​ ​ 5,256 ​ ​ 4,748 2023 ​ ​ 4,592 ​ ​ 3,849 2024 ​ ​ 4,335 ​ ​ 3,246 Remaining ​ ​ 16,951 ​ ​ 2,535 Total lease payments ​ $ 46,677 ​ $ 26,773 Less imputed interest ​ ​ (7,609) ​ ​ (5,161) Total discounted lease payments ​ $ 39,068 ​ $ 21,612 ​ As of December 31, 2019, the Company had a contract for an additional corporate office space that consists of approximately $16 million of undiscounted minimum lease payments. The operating lease has a nine-year lease term and is expected to commence in June 2020. As of December 31, 2018, minimum future contractual payments for long-term leases under the scope of ASC 840 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pipeline ​ Automobile and ​ ​ Real Estate ​ Transportation ​ Equipment Year ending December 31, ​ Leases ​ Agreement ​ Leases 2019 ​ $ 7,407 ​ $ 3,180 ​ $ 4,216 2020 ​ ​ 4,770 ​ ​ 3,180 ​ ​ 3,422 2021 ​ ​ 4,066 ​ ​ 3,180 ​ ​ 1,678 2022 ​ ​ 4,188 ​ ​ 3,180 ​ ​ 488 2023 ​ ​ 4,017 ​ ​ 3,180 ​ ​ 35 Remaining ​ ​ 25,140 ​ ​ 5,565 ​ ​ - Total lease payments ​ $ 49,588 ​ $ 21,465 ​ $ 9,839 ​

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2019
LONG-TERM DEBT [Abstract]
LONG-TERM DEBT	5 Long-term debt consisted of the following at December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Credit agreement ​ $ 375,000 ​ $ - 1.25% Convertible Senior Notes due 2020 ​ ​ 262,075 ​ ​ 562,075 5.75% Senior Notes due 2021 ​ ​ 773,609 ​ ​ 873,609 6.25% Senior Notes due 2023 ​ ​ 408,296 ​ ​ 408,296 6.625% Senior Notes due 2026 ​ ​ 1,000,000 ​ ​ 1,000,000 Total principal ​ ​ 2,818,980 ​ ​ 2,843,980 Unamortized debt discounts and premiums ​ ​ (2,575) ​ ​ (28,994) Unamortized debt issuance costs on notes ​ ​ (16,520) ​ ​ (22,665) Total long-term debt ​ $ 2,799,885 ​ $ 2,792,321 ​ Credit Agreement Whiting Oil and Gas, the Company’s wholly owned subsidiary, has a credit agreement with a syndicate of banks that as of December 31, 2019 had a borrowing base of $2.05 billion and aggregate commitments of $1.75 billion. As of December 31, 2019, the Company had $1.4 billion of available borrowing capacity under the credit agreement, which was net of $375 million of borrowings outstanding and $2 million in letters of credit outstanding. The borrowing base under the credit agreement is determined at the discretion of the lenders, based on the collateral value of the Company’s proved reserves that have been mortgaged to such lenders, and is subject to regular redeterminations on May 1 and November 1 of each year, as well as special redeterminations described in the credit agreement, in each case which may reduce the amount of the borrowing base. Upon a redetermination of the borrowing base, either on a periodic or special redetermination date, if total outstanding credit exposure exceeds the redetermined borrowing base, the Company will be required to prepay outstanding borrowings in an aggregate principal amount equal to such excess in six substantially equal monthly installments. In October 2019, the borrowing base under the credit agreement was reduced from $2.25 billion to $2.05 billion in connection with the semi-annual regular borrowing base redetermination, with no change to the aggregate commitments of $1.75 billion. A portion of the revolving credit facility in an aggregate amount not to exceed $50 million may be used to issue letters of credit for the account of Whiting Oil and Gas or other designated subsidiaries of the Company. As of December 31, 2019, $48 million was available for additional letters of credit under the agreement. The credit agreement provides for interest only payments until maturity, when the credit agreement expires and all outstanding borrowings are due. Interest under the credit agreement accrues at the Company’s option at either (i) a base rate for a base rate loan plus a margin between 0.50% and 1.50% based on the ratio of outstanding borrowings to the borrowing base, where the base rate is defined as the greatest of the prime rate, the federal funds rate plus 0.5% per annum, or an adjusted LIBOR rate plus 1.0% per annum, or (ii) an adjusted LIBOR rate for a Eurodollar loan plus a margin between 1.50% and 2.50% based on the ratio of outstanding borrowings to the borrowing base. Additionally, the Company incurs commitment fees of 0.375% or 0.50% based on the ratio of outstanding borrowings to the borrowing base on the unused portion of the aggregate commitments of the lenders under the credit agreement, which are included as a component of interest expense. At December 31, 2019, the weighted average interest rate on the outstanding principal balance under the credit agreement was 3.3%. The credit agreement matures on April 12, 2023, provided that if at any time and for so long as any senior notes (other than the 2020 Convertible Senior Notes) have a maturity date prior to 91 days after April 12, 2023, the maturity date shall be the date that is 91 days prior to the maturity of such senior notes. On September 13, 2019, the Company amended notes, including the convertible senior notes due in 2020 and the senior notes due in 2021, as permitted by the September 13, 2019 amendment to the credit agreement. Consequently, the Company has classified the credit agreement as long-term debt. The credit agreement contains restrictive covenants that may limit the Company’s ability to, among other things, incur additional indebtedness, sell assets, make loans to others, make investments, enter into mergers, enter into hedging contracts, incur liens and engage in certain other transactions without the prior consent of its lenders. Except for limited exceptions, the credit agreement also restricts the Company’s ability to make any dividend payments or distributions on its common stock. These restrictions apply to all of the Company’s restricted subsidiaries (as defined in the credit agreement). As of December 31, 2019, there were no retained earnings free from restrictions. The credit agreement requires the Company, as of the last day of any quarter, to maintain the following ratios (as defined in the credit agreement): (i) a consolidated current assets to consolidated current liabilities ratio (which includes an add back of the available borrowing capacity under the credit agreement) of not less than 1.0 to 1.0 and (ii) a total debt to last four quarters’ EBITDAX ratio of not greater than 4.0 to 1.0. As of December 31, 2019, the Company was in compliance with its covenants under the credit agreement. Under Whiting Oil and Gas’ credit agreement, a cross default provision provides that a default under certain other debt of the Company or certain of its subsidiaries in an aggregate principal amount exceeding $100 million may constitute an event of default under such credit agreement. Additionally, under the indentures governing our senior notes and senior convertible notes, a cross-default provision provides that a default under certain other debt of the Company or certain of its subsidiaries in an aggregate principal amount exceeding $100 million (or $50 million in the case of the 2021 Senior Notes) may constitute an event of default under such indenture. The obligations of Whiting Oil and Gas under the credit agreement are collateralized by a first lien on substantially all of Whiting Oil and Gas’ and Whiting Resource Corporation’s properties. The Company has guaranteed the obligations of Whiting Oil and Gas under the credit agreement and has pledged the stock of its subsidiaries as security for its guarantee. Senior Notes, Convertible Senior Notes and Senior Subordinated Notes Senior Notes and Senior Subordinated Notes In September 2013, the Company issued at par $1.1 billion of 5.0% Senior Notes due March 15, 2019 (the “2019 Senior Notes”) and $800 million of 5.75% Senior Notes due March 15, 2021, and issued at 101% of par an additional $400 million of 5.75% Senior Notes due March 15, 2021 (collectively, the “2021 Senior Notes”). The debt premium recorded in connection with the issuance of the 2021 Senior Notes is being amortized to interest expense over the term of the notes using the effective interest method, with an effective interest rate of 5.5% per annum. In March 2015, the Company issued at par $750 million of 6.25% Senior Notes due April 1, 2023 (the “2023 Senior Notes”). In December 2017, the Company issued at par $1.0 billion of 6.625% Senior Notes due January 15, 2026 (the “2026 Senior Notes” and together with the 2021 Senior Notes and the 2023 Senior Notes, the “Senior Notes”). The Company used the net proceeds from this offering to redeem in January 2018 all of the then outstanding 2019 Senior Notes. Refer to “Redemption of 2019 Senior Notes” below for more information on the redemption of the 2019 Senior Notes. During 2016, the Company exchanged (i) $75 million aggregate principal amount of its 2018 Senior Subordinated Notes, (ii) $139 million aggregate principal amount of its 2019 Senior Notes, (iii) $326 million aggregate principal amount of its 2021 Senior Notes, and (iv) $342 million aggregate principal amount of its 2023 Senior Notes, for the same aggregate principal amount of convertible notes. Subsequently during 2016, all $882 million aggregate principal amount of these convertible notes was converted into approximately 21.6 million shares of the Company’s common stock pursuant to the terms of the notes. Redemption of 2018 Senior Subordinated Notes. Redemption of 2019 Senior Notes. interest on the notes. The Company financed the redemption with proceeds from the issuance of the 2026 Senior Notes and borrowings under its credit agreement. As a result of the redemption, the Company recognized a $31 million loss on extinguishment of debt. Repurchases of 2021 Senior Notes. In October 2019, the Company paid an additional $72 million to repurchase $75 million aggregate principal amount of the 2021 Senior Notes, which payment consisted of the average 95.467% purchase price plus all accrued and unpaid interest on the notes. The Company financed the repurchases with borrowings under its credit agreement. As a result of the repurchases, the Company recognized a $3 million gain on extinguishment of debt, which included a noncash charge for the acceleration of unamortized debt issuance costs and debt premium on the notes. As of December 31, 2019, $774 million of 2021 Senior Notes remained outstanding. 2020 Convertible Senior Notes In September 2019, the Company paid $299 million to complete a cash tender offer for $300 million aggregate principal amount of the 2020 Convertible Senior Notes, which payment consisted of the 99.0% purchase price plus all accrued and unpaid interest on the notes, which were allocated to the liability and equity components based on their relative fair values. The Company financed the tender offer with borrowings under its credit agreement. As a result of the tender offer, the Company recognized a $4 million gain on extinguishment of debt, which was net of a $7 million charge for the non-cash write-off of unamortized debt issuance costs and debt discount and a $1 million charge for transaction costs. In addition, the Company recorded an $8 million reduction to the equity component of the 2020 Convertible Senior Notes. There was no deferred tax impact associated with this reduction due to the full valuation allowance in effect as of September 30, 2019. The remaining $262 million aggregate principal amount of 2020 Convertible Senior Notes outstanding as of December 31, 2019 are convertible exclusively at the holder’s option. Prior to January 1, 2020, the 2020 Convertible Senior Notes were convertible only upon the achievement of certain contingent market conditions. As of December 31, 2019, none of the contingent market conditions allowing holders of the 2020 Convertible Senior Notes to convert these notes had been met. On or after January 1, 2020, the 2020 Convertible Senior Notes are convertible at any time until the second scheduled trading day immediately preceding the April 1, 2020 maturity date of the notes. The notes are convertible at a current conversion rate of 6.4102 shares of Whiting’s common stock per $1,000 principal amount of the notes, which is equivalent to a current conversion price of approximately $156.00. The conversion rate will be subject to adjustment in some events. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase, in certain circumstances, the conversion rate for a holder who elects to convert its 2020 Convertible Senior Notes in connection with such corporate event. The Company has the option to settle conversions of these notes with cash, shares of common stock or a combination of cash and common stock at its election. The Company’s intent is to settle the principal amount of the 2020 Convertible Senior Notes in cash upon conversion. At maturity, the Company must settle all outstanding 2020 Convertible Senior Notes in cash. The Company’s business plan includes the intent to settle the outstanding 2020 Convertible Senior Notes using borrowings under its credit agreement. Accordingly, the outstanding balance has been classified as long-term debt in the consolidated balance sheet as of December 31, 2019. Upon issuance, the Company separately accounted for the liability and equity components of the 2020 Convertible Senior Notes. The liability component was recorded at the estimated fair value of a similar debt instrument without the conversion feature. The difference between the principal amount of the 2020 Convertible Senior Notes and the estimated fair value of the liability component was recorded as a debt discount and is being amortized to interest expense over the term of the notes using the effective interest method, with an effective interest rate of 5.6% per annum. The fair value of the liability component of the 2020 Convertible Senior Notes as of the issuance date was estimated at $1.0 billion, resulting in a debt discount at inception of $238 million. The equity component, representing the value of the conversion option, was computed by deducting the fair value of the liability component from the initial proceeds of the 2020 Convertible Senior Notes issuance. This equity component was recorded, net of deferred taxes and issuance costs, in additional paid-in capital within shareholders’ equity, and will not be remeasured as long as it continues to meet the conditions for equity classification. Transaction costs related to the 2020 Convertible Senior Notes issuance were allocated to the liability and equity components based on their relative fair values. Issuance costs attributable to the liability component were recorded as a reduction to the carrying value of long-term debt on the consolidated balance sheet and are being amortized to interest expense over the term of the notes using the effective interest method. Issuance costs attributable to the equity component were recorded as a charge to additional paid-in capital within shareholders’ equity. The 2020 Convertible Senior Notes consisted of the following at December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Liability component ​ ​ ​ ​ ​ ​ Principal ​ $ 262,075 ​ $ 562,075 Less: unamortized note discount ​ ​ (2,829) ​ ​ (29,504) Less: unamortized debt issuance costs ​ ​ (220) ​ ​ (2,340) Net carrying value ​ $ 259,026 ​ $ 530,231 Equity component (1) ​ $ 128,452 ​ $ 136,522 (1) Recorded in additional paid-in capital, net of $5 million of issuance costs and $50 million of deferred taxes as of December 31, 2019 and 2018. Interest expense recognized on the 2020 Convertible Senior Notes related to the stated interest rate and amortization of the debt discount totaled $26 million, $29 million and $28 million for the years ended December 31, 2019, 2018 and 2017, respectively. Security and Guarantees The Senior Notes and the 2020 Convertible Senior Notes are unsecured obligations of Whiting Petroleum Corporation and these unsecured obligations are subordinated to all of the Company’s secured indebtedness, which consists of Whiting Oil and Gas’ credit agreement. The Company’s obligations under the Senior Notes and the 2020 Convertible Senior Notes are guaranteed by the Company’s 100%-owned subsidiaries, Whiting Oil and Gas, Whiting US Holding Company, Whiting Canadian Holding Company ULC and Whiting Resources Corporation (the “Guarantors”). These guarantees are full and unconditional and joint and several among the Guarantors. Any subsidiaries other than these Guarantors are minor subsidiaries as defined by Rule 3-10(h)(6) of Regulation S-X of the SEC. Whiting Petroleum Corporation has no assets or operations independent of this debt and its investments in its consolidated subsidiaries.

ASSET RETIREMENT OBLIGATIONS

ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2019
ASSET RETIREMENT OBLIGATIONS [Abstract]
ASSET RETIREMENT OBLIGATIONS	6. ASSET RETIREMENT OBLIGATIONS The Company’s asset retirement obligations represent the present value of estimated future costs associated with the plugging and abandonment of oil and gas wells, removal of equipment and facilities from leased acreage, and land restoration (including removal of certain onshore and offshore facilities in California) in accordance with applicable local, state and federal laws and the terms of the Company’s lease agreements. The current portions as of December 31, 2019 and 2018 were $4 million and have been included in accrued liabilities and other in the consolidated balance sheets. The following table provides a reconciliation of the Company’s asset retirement obligations for the years ended December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2019 ​ 2018 Asset retirement obligation at January 1 ​ $ 135,834 ​ $ 134,237 Additional liability incurred ​ ​ 2,097 ​ ​ 11,981 Revisions to estimated cash flows ​ ​ (10,945) ​ ​ (17,197) Accretion expense ​ ​ 11,602 ​ ​ 11,405 Obligations on sold properties ​ ​ (2,078) ​ ​ (676) Liabilities settled ​ ​ (1,617) ​ ​ (3,916) Asset retirement obligation at December 31 ​ $ 134,893 ​ $ 135,834 ​

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2019
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	7. DERIVATIVE FINANCIAL INSTRUMENTS The Company is exposed to certain risks relating to its ongoing business operations, and it uses derivative instruments to manage its commodity price risk. In addition, the Company periodically enters into contracts that contain embedded features which are required to be bifurcated and accounted for separately as derivatives. Commodity Derivative Contracts — Crude Oil Collars, Swaps and Options. The table below details the Company’s collar, swap and option derivatives entered into to hedge forecasted crude oil production revenues as of December 31, 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Prices Commodity ​ Settlement Period ​ Index ​ Derivative Instrument ​ Contracted Crude Oil Volumes (Bbl) (1) ​ Swap Price ​ Sub-Floor ​ Floor ​ Ceiling Crude Oil ​ 2020 ​ NYMEX WTI ​ Fixed Price Swaps ​ 4,883,000 ​ $57.57 ​ - ​ - ​ - Crude Oil ​ 2020 ​ NYMEX WTI ​ Two-way Collars ​ 1,648,000 ​ - ​ - ​ $54.33 ​ $61.77 Crude Oil ​ 2020 ​ NYMEX WTI ​ Three-way Collars (2) ​ 3,658,000 ​ - ​ $43.50 ​ $54.00 ​ $63.63 Crude Oil ​ 2021 ​ NYMEX WTI ​ Three-way Collars (2) ​ 1,095,000 ​ - ​ $42.50 ​ $52.50 ​ $59.08 Crude Oil ​ 2021 ​ NYMEX WTI ​ Call Option (3) ​ 365,000 ​ - ​ - ​ - ​ $65.00 ​ ​ ​ ​ ​ ​ Total ​ 11,649,000 ​ ​ ​ ​ ​ ​ ​ ​ (1) Subsequent to December 31, 2019, the Company entered into additional two-way collars for 1,373,000 Bbl of crude oil volumes for the remainder of 2020 and additional three-way collars for 730,000 Bbl of crude oil volumes for 2021. (2) The Company is contracted to pay deferred premiums related to certain three-way collars at each settlement date. The weighted average premium for all three-way collars was $0.56 per Bbl as of December 31, 2019. (3) This derivative instrument is a sold call option. Crude Oil Sales and Delivery Contract. Embedded Derivatives — Derivative Instrument Reporting — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss Recognized in Income Not Designated as ​ Statement of Operations ​ Year Ended December 31, ASC 815 Hedges Classification 2019 2018 ​ 2017 Commodity contracts ​ Derivative loss, net ​ $ 53,769 ​ $ 17,170 ​ $ 104,138 Embedded derivatives ​ Loss on sale of properties ​ ​ - ​ ​ - ​ ​ 18,709 Total ​ ​ ​ $ 53,769 ​ $ 17,170 ​ $ 122,847 ​ Offsetting of Derivative Assets and Liabilities. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ Gross ​ ​ ​ ​ Recognized ​ ​ ​ ​ Recognized ​ Gross ​ Fair Value Not Designated as ​ ​ ​ Assets/ ​ Amounts ​ Assets/ ASC 815 Hedges Balance Sheet Classification Liabilities Offset Liabilities Derivative assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Derivative assets ​ $ 75,654 ​ $ (74,768) ​ $ 886 Commodity contracts - non-current ​ Other long-term assets ​ ​ 5,648 ​ ​ (5,648) ​ ​ - Total derivative assets ​ ​ ​ $ 81,302 ​ $ (80,416) ​ $ 886 Derivative liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Accrued liabilities and other ​ $ 85,053 ​ $ (74,768) ​ $ 10,285 Commodity contracts - non-current ​ Other long-term liabilities ​ ​ 6,534 ​ ​ (5,648) ​ ​ 886 Total derivative liabilities ​ ​ ​ $ 91,587 ​ $ (80,416) ​ $ 11,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ Gross ​ ​ ​ ​ Recognized ​ ​ ​ ​ Recognized ​ Gross ​ Fair Value Not Designated as ​ ​ ​ Assets/ ​ Amounts ​ Assets/ ASC 815 Hedges Balance Sheet Classification Liabilities Offset Liabilities Derivative assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Derivative assets ​ $ 69,735 ​ $ (1,393) ​ $ 68,342 Total derivative assets ​ ​ ​ $ 69,735 ​ $ (1,393) ​ $ 68,342 Derivative liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Accrued liabilities and other ​ $ 1,393 ​ $ (1,393) ​ $ - Total derivative liabilities ​ ​ ​ $ 1,393 ​ $ (1,393) ​ $ - (1) Because counterparties to the Company’s financial derivative contracts subject to master netting arrangements are lenders under Whiting Oil and Gas’ credit agreement, which eliminates its need to post or receive collateral associated with its derivative positions, columns for cash collateral pledged or received have not been presented in these tables. Contingent Features in Financial Derivative Instruments.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2019
FAIR VALUE MEASUREMENTS [Abstract]
FAIR VALUE MEASUREMENTS	8. FAIR VALUE MEASUREMENTS The Company follows FASB ASC Topic 820 – Fair Value Measurement and Disclosure ● Level 1: Quoted Prices in Active Markets for Identical Assets – inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets. ● Level 2: Significant Other Observable Inputs – inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. ● Level 3: Significant Unobservable Inputs – inputs to the valuation methodology are unobservable and significant to the fair value measurement. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. Cash, cash equivalents, accounts receivable and accounts payable are carried at cost, which approximates their fair value because of the short-term maturity of these instruments. The Company’s credit agreement has a recorded value that approximates its fair value since its variable interest rate is tied to current market rates and the applicable margins represent market rates. The Company’s senior notes are recorded at cost and the convertible senior notes are recorded at fair value at the date of issuance. The following table summarizes the fair values and carrying values of these instruments as of December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ December 31, 2018 ​ ​ Fair ​ Carrying ​ Fair ​ Carrying ​ Value (1) Value (2) Value (1) Value (2) 1.25% Convertible Senior Notes due 2020 ​ $ 260,214 ​ $ 259,026 ​ $ 531,161 ​ $ 530,231 5.75% Senior Notes due 2021 ​ ​ 732,995 ​ ​ 772,080 ​ ​ 829,929 ​ ​ 870,545 6.25% Senior Notes due 2023 ​ ​ 343,989 ​ ​ 405,392 ​ ​ 375,632 ​ ​ 404,659 6.625% Senior Notes due 2026 ​ ​ 681,250 ​ ​ 988,387 ​ ​ 865,000 ​ ​ 986,886 Total ​ $ 2,018,448 ​ $ 2,424,885 ​ $ 2,601,722 ​ $ 2,792,321 (1) Fair values are based on quoted market prices for these debt securities, and such fair values are therefore designated as Level 1 within the valuation hierarchy. (2) Carrying values are presented net of unamortized debt issuance costs and debt discounts or premiums. The Company’s derivative financial instruments are recorded at fair value and include a measure of the Company’s own nonperformance risk or that of its counterparty, as appropriate. The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2019 and 2018, and indicate the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair values (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fair Value ​ Level 1 Level 2 Level 3 December 31, 2019 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 886 ​ $ - ​ $ 886 Total financial assets ​ $ - ​ $ 886 ​ $ - ​ $ 886 Financial Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 10,285 ​ $ - ​ $ 10,285 Commodity derivatives – non-current ​ ​ - ​ ​ 886 ​ ​ - ​ ​ 886 Total financial liabilities ​ $ - ​ $ 11,171 ​ $ - ​ $ 11,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fair Value ​ Level 1 Level 2 Level 3 December 31, 2018 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 68,342 ​ $ - ​ $ 68,342 Total financial assets ​ $ - ​ $ 68,342 ​ $ - ​ $ 68,342 ​ The following methods and assumptions were used to estimate the fair values of the Company’s financial assets and liabilities that are measured on a recurring basis: Commodity Derivatives In addition, the Company had a long-term crude oil sales and delivery contract, whereby it had committed to deliver certain fixed volumes of crude oil produced from its Redtail field in Colorado. Whiting determined that the contract did not meet the “normal purchase normal sale” exclusion, and therefore reflected this contract at fair value in its consolidated financial statements prior to settlement. This commodity derivative was valued based on a probability-weighted income approach which considered various assumptions, including quoted spot prices for commodities, market differentials for crude oil, U.S. Treasury rates and either the Company’s or the counterparty’s nonperformance risk, as appropriate. The assumptions used in the valuation of the crude oil sales and delivery contract included certain market differential metrics that were unobservable during the term of the contract. Such unobservable inputs were significant to the contract valuation methodology, and the contract’s fair value was therefore designated as Level 3 within the valuation hierarchy. On February 1, 2018, Whiting paid $61 million to the counterparty to settle all future minimum volume commitments under this agreement. Accordingly, this derivative was settled in its entirety as of that date. Level 3 Fair Value Measurements — ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2018 Fair value liability, beginning of period ​ $ (63,278) Unrealized gains on commodity derivative contracts included in earnings (1) ​ ​ 2,242 Settlement of commodity derivative contracts ​ ​ 61,036 Transfers into (out of) Level 3 ​ ​ - Fair value liability, end of period ​ $ - (1) Included in derivative loss, net in the consolidated statements of operations. Non-recurring Fair Value Measurements — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss (Before ​ ​ Net Carrying ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Tax) Year ​ ​ Value as of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ended ​ ​ December 31, ​ Fair Value Measurements Using ​ December 31, ​ 2017 Level 1 Level 2 Level 3 2017 Proved property (1) ​ $ 389,390 ​ $ - ​ $ - ​ $ 389,390 ​ $ 834,950 (1) During the fourth quarter of 2017, proved oil and gas properties at the Redtail field in the Denver-Julesburg Basin (the “DJ Basin”) in Weld County, Colorado, with a previous carrying amount of $1.2 billion were written down to their fair value as of December 31, 2017 of $389 million, resulting in a non-cash impairment charge of $835 million which was recorded within exploration and impairment expense. The following methods and assumptions were used to estimate the fair values of the non-financial assets in the table above: Proved Property Impairments

SHAREHOLDERS' EQUITY AND NONCON

SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST	12 Months Ended
	Dec. 31, 2019
SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST [Abstract]
SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST	9. SHAREHOLDERS’ EQUITY AND NONCONTROLLING INTEREST Common Stock Reverse Stock Split. four Noncontrolling Interest ​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2017 Balance at beginning of period ​ $ 7,962 Net loss ​ ​ (14) Conveyance of ownership interest ​ ​ (7,948) Balance at end of period ​ $ - ​

REVENUE RECOGNITION

REVENUE RECOGNITION	12 Months Ended
	Dec. 31, 2019
REVENUE RECOGNITION [Abstract]
REVENUE RECOGNITION	​ 10. REVENUE RECOGNITION The Company recognizes revenue in accordance with FASB ASC Topic 606 – Revenue from Contracts with Customers ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 OPERATING REVENUES ​ ​ ​ ​ ​ ​ Oil sales ​ $ 1,492,218 ​ $ 1,850,052 NGL and natural gas sales ​ ​ 80,027 ​ ​ 231,362 Oil, NGL and natural gas sales ​ $ 1,572,245 ​ $ 2,081,414 ​ Whiting receives payment for product sales from one The Company has elected to utilize the practical expedient in ASC 606 that states the Company is not required to disclose the transaction price allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation. Under the Company’s contracts, each monthly delivery of product represents a separate performance obligation, therefore, future volumes are wholly unsatisfied, and disclosure of the transaction price allocated to remaining performance obligations is not required.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2019
STOCK-BASED COMPENSATION [Abstract]
STOCK-BASED COMPENSATION	11. STOCK-BASED COMPENSATION Equity Incentive Plan The Company grants service-based RSAs and RSUs to executive officers and employees, which generally vest ratably over a three-year service period. The Company also grants service-based RSAs to directors, which generally vest over a one-year service period. In addition, the Company grants PSAs and PSUs to executive officers that are subject to market-based vesting criteria, which generally vest over a three-year service period. The Company accounts for forfeitures of awards granted under these plans as they occur in determining compensation expense. The Company recognizes compensation expense for awards subject to market-based vesting conditions regardless of whether it becomes probable that these conditions will be achieved or not, and compensation expense for share-settled awards is not reversed if vesting does not actually occur. During 2019, 2018 and 2017, 467,055, 249,983 and 538,194 shares, respectively, of service-based RSAs and RSUs were granted to employees, executive officers and directors under the 2013 Equity Plan. The Company determines compensation expense for these share-settled awards using their fair value at the grant date, which is based on the closing bid price of the Company’s common stock on such date. The weighted average grant date fair value of service-based RSAs and RSUs was $24.65 per share, $32.34 per share and $40.66 per share for the years ended December 31, 2019, 2018, and 2017, respectively. During 2019 and 2018, 774,665 and 308,432 shares, respectively, of service-based RSUs were granted to employees under the 2013 Equity Plan. These awards will be settled in cash and are recorded as a liability in the consolidated balance sheets. The Company determines compensation expense for cash-settled RSUs using the fair value at the end of each reporting period, which is based on the closing bid price of the Company’s common stock on such date. During 2019 and 2018, 347,493 and 230,932 shares, respectively, of PSAs and PSUs subject to certain market-based vesting criteria were granted to executive officers under the 2013 Equity Plan. The market-based awards cliff vest on the third anniversary of the grant date, and the number of shares that will vest at the end of that three-year performance period is determined based on the rank of Whiting’s cumulative stockholder return compared to the stockholder return of a peer group of companies on each anniversary of the grant date over the three-year performance period. The number of awards earned could range from zero up to two times the number of shares initially granted. However, awards earned up to the target shares granted (or 100%) will be settled in shares, while awards earned in excess of the target shares granted will be settled in cash. The cash-settled component of such awards is recorded as a liability in the consolidated balance sheets and will be remeasured at fair value using a Monte Carlo valuation model at the end of each reporting period. During 2017, 168,466 PSAs subject to certain market-based vesting criteria were granted to executive officers under the 2013 Equity Plan. These market-based awards cliff vest on the third anniversary of the grant date, and the number of shares that will vest at the end of that three-year performance period is determined based on the rank of Whiting’s cumulative stockholder return compared to the stockholder return of a peer group of companies over the same three-year period. The number of shares earned could range from zero up to two times the number of shares initially granted and will be settled entirely in shares. For awards subject to market conditions, the grant date fair value is estimated using a Monte Carlo valuation model. The Monte Carlo model is based on random projections of stock price paths and must be repeated numerous times to achieve a probabilistic assessment. Expected volatility is calculated based on the historical volatility and implied volatility of Whiting’s common stock, and the risk-free interest rate is based on U.S. Treasury yield curve rates with maturities consistent with the three-year vesting period. The key assumptions used in valuing these market-based awards were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 2018 ​ 2017 Number of simulations 2,500,000 2,500,000 ​ 2,500,000 Expected volatility 72.95% ​ 72.80% ​ 82.44% Risk-free interest rate 2.60% ​ 2.12% ​ 1.52% Dividend yield — — ​ — ​ The weighted average grant date fair value of the market-based awards that will be settled in shares as determined by the Monte Carlo valuation model was $25.97 per share, $27.28 per share and $63.04 per share in 2019, 2018 and 2017, respectively. The following table shows a summary of the Company’s service-based and market-based awards activity for the year ended December 31, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Awards ​ Weighted Average ​ ​ Service ‑ Based ​ Market-Based ​ Grant Date ​ RSAs & RSUs PSAs & PSUs Fair Value Nonvested awards, January 1 554,527 503,696 ​ $ 34.94 Granted 467,055 347,493 ​ 24.61 Vested (383,908) (98,581) ​ 32.15 Forfeited (170,172) (304,221) ​ 32.88 Nonvested awards, December 31 467,502 448,387 ​ $ 28.28 ​ As of December 31, 2019, there was $13 million of total unrecognized compensation cost related to unvested awards granted under the stock incentive plans. That cost is expected to be recognized over a weighted average period of 2.0 years. For the years ended December 31, 2019, 2018 and 2017, the total fair value of the Company’s service-based and market-based awards vested was $12 million, $16 million and $15 million, respectively. Stock Options The following table shows a summary of the Company’s stock options outstanding as of December 31, 2019 as well as activity during the year then ended: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ Weighted ​ Aggregate ​ Remaining ​ ​ ​ ​ Average ​ Intrinsic ​ Contractual ​ ​ Number of ​ Exercise Price ​ Value ​ Term ​ Options per Share (in thousands) (in years) Options outstanding at January 1 49,230 ​ $ 195.92 ​ Granted - ​ - ​ Exercised - ​ - ​ $ - Forfeited or expired (6,270) ​ 216.78 ​ Options outstanding at December 31 42,960 ​ $ 192.88 ​ $ - 2.2 Options vested at December 31 42,960 ​ $ 192.88 ​ $ - 2.2 Options exercisable at December 31 42,960 ​ $ 192.88 ​ $ - 2.2 ​ There was no unrecognized compensation cost related to unvested stock option awards as of December 31, 2019. For the year ended December 31, 2018, the aggregate intrinsic value of stock options exercised was $0.1 million. There were no stock options exercised during the years ended December 31, 2019 or 2017. Total stock-based compensation expense was $8 million, $18 million and $22 million for the years ended December 31, 2019, 2018 and 2017, respectively.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
INCOME TAXES [Abstract]
INCOME TAXES	12. INCOME TAXES Income tax expense (benefit) consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 Current income tax expense (benefit) ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ - ​ $ - ​ $ (7,305) State ​ ​ - ​ ​ - ​ ​ 14 Total current income tax benefit ​ ​ - ​ ​ - ​ ​ (7,291) Deferred income tax expense (benefit) ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ 2,140 ​ ​ (10,960) ​ ​ (398,686) State ​ ​ (3,513) ​ ​ 12,333 ​ ​ (77,002) Foreign ​ ​ 73,593 ​ ​ - ​ ​ - Total deferred income tax expense (benefit) ​ ​ 72,220 ​ ​ 1,373 ​ ​ (475,688) Total ​ $ 72,220 ​ $ 1,373 ​ $ (482,979) ​ Income tax expense (benefit) differed from amounts that would result from applying the U.S. statutory income tax rate (21% for the years ended December 31, 2019 and 2018 and 35% for the year ended December 31, 2017) to income before income taxes as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 U.S. statutory income tax expense (benefit) ​ $ (35,479) ​ $ 72,211 ​ $ (602,219) State income taxes, net of federal benefit ​ ​ (8,288) ​ ​ 14,324 ​ ​ (39,557) Foreign tax expense ​ ​ (147) ​ ​ - ​ ​ - Valuation allowance ​ ​ 39,672 ​ ​ (87,774) ​ ​ 120,880 Federal tax reform ​ ​ - ​ ​ - ​ ​ (42,033) Impairment charge after enactment of federal tax reform ​ ​ - ​ ​ - ​ ​ 114,293 IRC Section 382 limitation ​ ​ - ​ ​ - ​ ​ (45,899) Market-based equity awards ​ ​ 910 ​ ​ 2,215 ​ ​ 7,003 Outside basis difference recognition ​ ​ 73,740 ​ ​ - ​ ​ - Other ​ ​ 1,812 ​ ​ 397 ​ ​ 4,553 Total ​ $ 72,220 ​ $ 1,373 ​ $ (482,979) ​ The principal components of the Company’s deferred income tax assets and liabilities at December 31, 2019 and 2018 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 Deferred income tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforward ​ $ 944,709 ​ $ 873,646 Derivative instruments ​ ​ 2,451 ​ ​ - Asset retirement obligations ​ ​ 32,152 ​ ​ 32,546 Restricted stock compensation ​ ​ 2,033 ​ ​ 5,603 EOR credit carryforwards ​ ​ 7,946 ​ ​ 7,946 Lease obligations ​ ​ 14,463 ​ ​ - Other ​ ​ 12,847 ​ ​ 10,777 Total deferred income tax assets ​ ​ 1,016,601 ​ ​ 930,518 Less valuation allowance ​ ​ (188,281) ​ ​ (152,035) Net deferred income tax assets ​ ​ 828,320 ​ ​ 778,483 Deferred income tax liabilities ​ ​ ​ ​ ​ ​ Oil and gas properties ​ ​ 805,989 ​ ​ 740,933 Trust distributions ​ ​ 10,517 ​ ​ 15,479 Lease assets ​ ​ 10,993 ​ ​ - Derivative instruments ​ ​ - ​ ​ 16,375 Discount on convertible senior notes ​ ​ 674 ​ ​ 7,069 Foreign outside basis difference ​ ​ 73,740 ​ ​ - Total deferred income tax liabilities ​ ​ 901,913 ​ ​ 779,856 Total net deferred income tax liabilities ​ $ 73,593 ​ $ 1,373 ​ The Company’s July 1, 2016 note exchange transactions triggered an ownership shift within the meaning of Section 382 of the Internal Revenue Code (“IRC”) due to the “deemed share issuance” that resulted from the note exchanges. The ownership shift will limit Whiting’s usage of certain of its net operating losses (“NOLs”) and tax credits in the future. Accordingly, the Company recognized valuation allowances on its deferred tax assets totaling $259 million. In the third quarter of 2017 there was a partial release of this valuation allowance in the amount of $41 million associated with built-on gains on the sale of the FBIR Assets. As of December 31, 2019, the Company had federal NOL carryforwards of $3.4 billion, which is net of the IRC Section 382 limitation. The Company also has various state NOL carryforwards. The determination of the state NOL carryforwards is dependent upon apportionment percentages and state laws that can change from year to year and that can thereby impact the amount of such carryforwards. If unutilized, the majority of the federal NOLs will expire between 2023 and 2037 and the state NOLs will expire between 2020 and 2037. Any federal NOLs generated in 2018 or subsequent do not expire. EOR credits are a credit against federal income taxes for certain costs related to extracting high-cost oil, utilizing certain prescribed enhanced tertiary recovery methods. As of December 31, 2019, the Company had recognized aggregate EOR credits of $8 million. As a result of the IRC Section 382 limitation in July 2016, the Company recorded a full valuation allowance on these credits. On December 22, 2017, Congress passed the Tax Cuts and Jobs Act (the “TCJA”). The legislation significantly changed the U.S. corporate tax law by, among other things, lowering the U.S. corporate income tax rate from 35% to 21% beginning in January 2018, implementing a territorial tax system and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. FASB ASC Topic 740 – Income Taxes Amounts recorded during the year ended December 31, 2017 related to the TCJA principally relate to the reduction in the U.S. corporate income tax rate to 21%, which resulted in (i) income tax expense of $51 million from the revaluation of the Company’s deferred tax assets and liabilities as of the date of enactment and (ii) an income tax benefit totaling $93 million related to a reduction in the Company’s existing valuation allowances. Other elements of the TCJA that did not have an impact on the Company’s financial statements upon enactment of the TCJA, but may impact the Company’s income taxes in future periods include: (i) IRC Section 168(k) first-year optional bonus depreciation, (ii) repeal of the corporate alternative minimum tax, (iii) limitation on the usage of NOLs generated after 2017 to 80% of taxable income, (iv) additional limitations on certain meals and entertainment expenses, (v) repeal of the deduction for income attributable to domestic production activities, (vi) like-kind exchange limitations for property other than real property, (vii) ability to capitalize and amortize intangible drilling costs under IRC Section 59(e), and (viii) interest deduction limitations under IRC Section 163(j). In assessing the realizability of deferred tax assets (“DTAs”), management considers whether it is more likely than not that some portion, or all, of the Company’s DTAs will not be realized. In making such determination, the Company considers all available positive and negative evidence, including future reversals of temporary differences, tax-planning strategies and projected future taxable income and results of operations. If the Company concludes that it is more likely than not that some portion, or all, of its DTAs will not be realized, the tax asset is reduced by a valuation allowance. At December 31, 2019, the Company had a valuation allowance totaling $188 million, comprised of $138 million of NOL carryforward limitations under Section 382 of the IRC, $8 million of EOR credits, which will expire between 2023 and 2025, $1 million of short-term capital loss carryforwards that are not expected to be realized and a $41 million general valuation allowance against the Company’s net U.S. deferred tax assets. During the fourth quarter of 2019, the Company determined it no longer had the ability to indefinitely prevent the reversal of the outside basis difference related to Whiting Canadian Holding Company ULC, Whiting’s wholly owned subsidiary, which owns a portion of Whiting’s U.S. assets obtained through the acquisition of Kodiak Oil and Gas Corporation during 2014. Accordingly, the Company revised its assessment related to noncurrent Canadian deferred taxes pursuant to ASC 740-30-25-17 and recognized a $74 million deferred tax liability as well as the same amount of deferred income tax expense as of and for the year ended December 31, 2019 associated with the outside basis difference related to Whiting Canadian Holding Company ULC. During 2018, the Company recorded an adjustment to its valuation allowance on DTAs totaling $30 million. At December 31, 2018, the Company had a valuation allowance totaling $152 million, comprised of $138 million of NOL carryforward limitations under Section 382 of the IRC, $8 million of EOR credits, which will expire between 2023 and 2025, $5 million of Canadian NOL carryforwards, which will expire between 2034 and 2035, and $1 million of short-term capital loss carryforwards that are not expected to be realized. As of December 31, 2019 and 2018, the Company did not have any uncertain tax positions. For the years ended December 31, 2019, 2018 and 2017, the Company did not recognize any interest or penalties with respect to unrecognized tax benefits, nor did the Company have any such interest or penalties previously accrued. The Company believes that it is reasonably possible that no increases to unrecognized tax benefits will occur in the next twelve months. The Company files income tax returns in the U.S. federal jurisdiction and in various states, each with varying statutes of limitations. The 2015 through 2019 tax years generally remain subject to examination by federal and state tax authorities. Additionally, the Company has Canadian income tax filings which remain subject to examination by the related tax authorities for the 2014 through 2019 tax years.

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2019
EARNINGS PER SHARE [Abstract]
EARNINGS PER SHARE	13. EARNINGS PER SHARE The reconciliations between basic and diluted earnings (loss) per share are as follows (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 ​ 2017 Basic Earnings (Loss) Per Share ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common shareholders ​ $ (241,166) ​ $ 342,494 ​ $ (1,237,648) Weighted average shares outstanding, basic ​ ​ 91,285 ​ ​ 90,953 ​ ​ 90,683 Earnings (loss) per common share, basic ​ $ (2.64) ​ $ 3.77 ​ $ (13.65) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted Earnings (Loss) Per Share ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common shareholders ​ $ (241,166) ​ $ 342,494 ​ $ (1,237,648) Weighted average shares outstanding, basic ​ ​ 91,285 ​ ​ 90,953 ​ ​ 90,683 Service-based awards, market-based awards and stock options ​ ​ - ​ ​ 916 ​ ​ - Weighted average shares outstanding, diluted ​ ​ 91,285 ​ ​ 91,869 ​ ​ 90,683 Earnings (loss) per common share, diluted ​ $ (2.64) ​ $ 3.73 ​ $ (13.65) ​ For the year ended December 31, 2019 the Company had a net loss and therefore the diluted earnings per share calculation for that period excludes the anti-dilutive effect of 344,671 shares of service-based awards and 3,511 shares of market-based awards. In addition, the diluted earnings per share calculation for the year ended December 31, 2019 excludes the effect of 45,588 common shares for stock options that were out of the money as of December 31, 2019. For the year ended December 31, 2018, the diluted earnings per share calculation excludes the effect of 100,708 common shares for stock options that were out of the money as of December 31, 2018. For the year ended December 31, 2017, the Company had a net loss and therefore the diluted earnings per share calculation for that period excludes the anti-dilutive effect of 509,744 shares of service-based awards, 22,946 shares of market-based awards and 1,083 stock options. In addition, the diluted earnings per share calculation for the year ended December 31, 2017 excludes the effect of 123,775 common shares for stock options that were out-of-the-money and 345,071 shares of market-based awards that did not meet the market-based vesting criteria as of December 31, 2017. Refer to the “Stock-Based Compensation” footnote for further information on the Company’s service-based awards, market-based awards and stock options. As discussed in the “Long-Term Debt” footnote, the Company has the option to settle conversions of the 2020 Convertible Senior Notes with cash, shares of common stock or any combination thereof. Based on the current conversion price, the entire outstanding principal amount of the 2020 Convertible Senior Notes as of December 31, 2019 would be convertible into approximately 1.7 million shares of the Company’s common stock. However, the Company’s intent is to settle the principal amount of the notes in cash upon conversion. As a result, only the amount by which the conversion value exceeds the aggregate principal amount of the notes (the “conversion spread”) is considered in the diluted earnings per share computation under the treasury stock method. As of December 31, 2019, 2018 and 2017, the conversion value did not exceed the principal amount of the notes. Accordingly, there was no impact to diluted earnings per share or the related disclosures for those periods.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2019
COMMITMENTS AND CONTINGENCIES [Abstract]
COMMITMENTS AND CONTINGENCIES	The table below shows the Company’s minimum future payments due by period under unconditional purchase obligations as of December 31, 2019 (in thousands): ​ ​ ​ ​ ​ ​ Pipeline ​ ​ Transportation Year ending December 31, ​ Agreements 2020 ​ $ 2,189 2021 ​ ​ 2,189 2022 ​ ​ 2,189 2023 ​ ​ 2,189 2024 ​ ​ 547 Total payments ​ $ 9,303 ​ Pipeline Transportation Agreements — The remaining contract contains a commitment to transport a minimum volume of crude oil or else pay for any deficiencies at a price stipulated in the contract. Although minimum annual quantities are specified in the agreement, the actual oil volumes transported and their corresponding unit prices are variable over the term of the contract. As a result, the future minimum payments for each of the five succeeding fiscal years are not fixed and determinable and are not therefore included in the table above. As of December 31, 2019, the Company estimated the minimum future commitments under this transportation agreement to approximate $9 million through 2022. During 2019, 2018 and 2017, the cost of transportation of crude oil, natural gas and NGLs under these contracts amounted to $2 million, $2 million and $2 million, respectively. Purchase Contracts As a result of the Company’s reduced development operations in its Redtail field, Whiting has made and expects to make periodic deficiency payments under this purchase contract during the remaining term, which expires in 2020. During 2019, 2018 and 2017, purchases of water under the Company’s take-or-pay arrangement amounted to $8 million, $8 million and $22 million, respectively, which included $8 million and $2 million of deficiency payments for the years ended December 31, 2019 and 2018, respectively, and insignificant deficiency payments for the year ended December 31, 2017. Water Disposal Agreement Delivery Commitments The second delivery contract is tied to oil production in the Williston Basin. The effective date of this contract is contingent upon the completion of certain related pipelines, which are currently expected to be brought online in 2021. Under the terms of the agreement, Whiting has committed to deliver 10 MBbl/d for a term of seven years. The Company believes its production and reserves in the Williston Basin are sufficient to fulfill this delivery commitment, and therefore expects to avoid any payments for deficiencies under this contract. The third delivery contract is tied to crude oil production at Whiting’s Redtail field in Weld County, Colorado. As of December 31, 2019, this contract contains remaining delivery commitments of 4.1 MMBbl of crude oil through the end of the contract’s term in April 2020. The Company has determined that it is not probable that future oil production from its Redtail field will be sufficient to meet the minimum volume requirements specified in these physical delivery contracts, and as a result, the Company expects to make periodic deficiency payments for any shortfalls in delivering the minimum committed volumes. During 2019, 2018 and 2017, total deficiency payments under these contracts, as well as a previous Redtail contract that was terminated in February 2018, amounted to $64 million, $39 million and $66 million, respectively. The Company recognizes any monthly deficiency payments in the period in which the underdelivery takes place and the related liability has been incurred. The table above does not include any such deficiency payments that may be incurred under the Company’s physical delivery contracts, since it cannot be predicted with accuracy the amount and timing of any such penalties incurred. Litigation

CAPITALIZED EXPLORATORY WELL CO

CAPITALIZED EXPLORATORY WELL COSTS	12 Months Ended
	Dec. 31, 2019
CAPITALIZED EXPLORATORY WELL COSTS [Abstract]
CAPITALIZED EXPLORATORY WELL COSTS	15. CAPITALIZED EXPLORATORY WELL COSTS Exploratory well costs that are incurred and expensed in the same annual period have not been included in the table below. The net changes in capitalized exploratory well costs were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 Beginning balance at January 1 ​ $ - ​ $ 13,894 ​ $ - Additions to capitalized exploratory well costs pending the determination of proved reserves ​ ​ - ​ ​ 10,831 ​ ​ 13,894 Reclassifications to wells, facilities and equipment based on the determination of proved reserves ​ ​ - ​ ​ (24,725) ​ ​ - Ending balance at December 31 ​ $ - ​ $ - ​ $ 13,894 ​ At December 31, 2019, the Company had no costs capitalized for exploratory wells in progress for a period of greater than one year after the completion of drilling.

RESTRUCTURING

RESTRUCTURING	12 Months Ended
	Dec. 31, 2019
RESTRUCTURING [Abstract]
RESTRUCTURING	16. RESTRUCTURING On July 31, 2019, the Company executed a workforce reduction as part of an organizational redesign and cost reduction strategy to better align its business with the current operating environment and drive long-term value. In connection with these activities, the Company incurred $8 million in net restructuring costs associated with one-time employee termination benefits. These restructuring costs are included in general and administrative expenses in the consolidated statements of operations.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2019
SUBSEQUENT EVENTS [Abstract]
SUBSEQUENT EVENTS	17. SUBSEQUENT EVENTS On January 9, 2020, the Company completed the divestiture of its interests in 30 non-operated, producing oil and gas wells and related undeveloped acreage located in McKenzie County, North Dakota for aggregate sales proceeds of $25 million (before closing adjustments).

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Basis of Presentation of Consolidated Financial Statements	Basis of Presentation of Consolidated Financial Statements
Use of Estimates	Use of Estimates —
Cash and Cash Equivalents	Cash and Cash Equivalents
Accounts Receivable Trade	Accounts Receivable Trade The Company routinely assesses the recoverability of all material trade and other receivables to determine their collectability. At December 31, 2019 and 2018, the Company had an allowance for doubtful accounts of $9 million and $12 million, respectively.
Inventories	Inventories —
Oil and Gas Properties	Oil and Gas Properties Proved. The Company assesses its proved oil and gas properties for impairment whenever events or circumstances indicate that the carrying value of the assets may not be recoverable. Such events include, but are not limited to, declines in commodity prices, increases in operating costs, unfavorable reserve revisions, poor well performance, changes in development plans and potential property divestitures. The impairment test compares undiscounted future net cash flows to the assets’ net book value. These undiscounted cash flows are driven by significant assumptions, including the Company’s expected future development activity, reserve estimates, forecasted pricing, future operating costs, capital expenditures and severance taxes. If the net capitalized costs exceed undiscounted future net cash flows, then the cost of the property is written down to fair value utilizing a discounted future net cash flow analysis. Impairment expense for proved properties totaled $835 million for the year ended December 31, 2017, which is reported in exploration and impairment expense. Net carrying values of retired, sold or abandoned properties that constitute less than a complete unit of depreciable property are charged or credited, net of proceeds, to accumulated depreciation, depletion and amortization unless doing so significantly affects the unit-of-production amortization rate, in which case a gain or loss is recognized in income. Gains or losses from the disposal of complete units of depreciable property are recognized to earnings. Unproved. Exploratory. Costs of drilling exploratory wells are initially capitalized, pending determination of whether the well has found proved reserves. If an exploratory well has not found proved reserves, the costs of drilling the well and other associated costs are charged to expense. Costs incurred for exploratory wells that find reserves, which cannot yet be classified as proved, continue to be capitalized if (i) the well has found a sufficient quantity of reserves to justify completion as a producing well and (ii) the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project. If either condition is not met, or if the Company obtains information that raises substantial doubt about the economic or operational viability of the project, the exploratory well costs, net of any salvage value, are expensed.
Other Property and Equipment	Other Property and Equipment — buildings and leasehold improvements office equipment
Debt Issuance Costs	Debt Issuance Costs
Debt Discount and Premiums	Debt Discounts and Premiums
Derivative Instruments	Derivative Instruments Derivatives and Hedging instruments. All derivative instruments, other than those that meet the “normal purchase normal sale” exclusion, are recorded on the balance sheet as either an asset or liability measured at fair value. Gains and losses from changes in the fair value of derivative instruments are recognized immediately in earnings, unless the derivative meets specific hedge accounting criteria and the derivative has been designated as a hedge. The Company does not currently apply hedge accounting to any of its outstanding derivative instruments, and as a result, all changes in derivative fair values are recognized currently in earnings. Cash flows from derivatives used to manage commodity price risk are classified in operating activities along with the cash flows of the underlying hedged transactions. The Company does not enter into derivative instruments for speculative or trading purposes. Refer to the “Derivative Financial Instruments” footnote for further information.
Asset Retirement Obligations and Environmental Costs	Asset Retirement Obligations and Environmental Costs Asset Retirement and Environmental Obligations Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that obligations have been incurred and the amounts can be reasonably estimated. These liabilities are not reduced by possible recoveries from third parties.
Deferred Gain On Sale	Deferred Gain on Sale
Revenue Recognition	Revenue Recognition Revenue from Contracts with Customers Taxes collected and remitted to governmental agencies on behalf of customers are not included in revenues or costs and expenses.
General and Administrative Expenses	General and Administrative Expenses
Stock-based Compensation Expense	Stock-based Compensation Expense
401 (k) Plan	401(k) Plan
Acquisition Cost	Acquisition Costs —
Maintenance and Repairs	Maintenance and Repairs
Income Taxes	Income Taxes
Earnings Per Share	Earnings Per Share
Industry Segment and Geographic Information	Industry Segment and Geographic Information
Concentration of Credit Risk	Concentration of Credit Risk ​ ​ ​ ​ ​ Year Ended December 31, 2019 Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 12 % ​ ​ ​ ​ ​ Year Ended December 31, 2018 United Energy Trading, LLC ​ 17 % Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 11 % ​ ​ ​ ​ ​ Year Ended December 31, 2017 Tesoro Crude Oil Co 18 % ​ ​ ​ ​ ​ Commodity derivative contracts held by the Company are with nine counterparties, all of which are participants in Whiting’s credit facility and all of which have investment-grade ratings from Moody’s and Standard & Poor’s. As of December 31, 2019, outstanding derivative contracts with Capital One, N.A., JP Morgan Chase Bank, N.A., the Bank of Nova Scotia, Merrill Lynch Commodities, Inc. and Citibank, N.A. represented 28%, 16%, 14%, 13% and 11%, respectively, of total crude oil volumes hedged.
Adopted and Recently Issued Accounting Pronouncements	Adopted and Recently Issued Accounting Pronouncements — Leases

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Percentages of total oil and gas sales to significant purchasers	​ ​ ​ ​ ​ Year Ended December 31, 2019 Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 12 % ​ ​ ​ ​ ​ Year Ended December 31, 2018 United Energy Trading, LLC ​ 17 % Tesoro Crude Oil Co ​ 14 % Philips 66 Company ​ 11 % ​ ​ ​ ​ ​ Year Ended December 31, 2017 Tesoro Crude Oil Co 18 % ​ ​ ​ ​

OIL AND GAS PROPERTIES (Tables)

OIL AND GAS PROPERTIES (Tables)	12 Months Ended
	Dec. 31, 2019
OIL AND GAS PROPERTIES [Abstract]
Net capitalized costs related to oil and gas producing activities	Net capitalized costs related to the Company’s oil and gas producing activities at December 31, 2019 and 2018 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Costs of completed wells and facilities ​ $ 9,847,159 ​ $ 9,182,384 Proved leasehold costs ​ ​ 2,702,236 ​ ​ 2,729,593 Wells and facilities in progress ​ ​ 159,334 ​ ​ 160,995 Unproved leasehold costs ​ ​ 103,278 ​ ​ 122,687 Total oil and gas properties, successful efforts method ​ ​ 12,812,007 ​ ​ 12,195,659 Accumulated depletion ​ ​ (5,656,929) ​ ​ (4,937,579) Oil and gas properties, net ​ $ 7,155,078 ​ $ 7,258,080

ACQUISITIONS AND DIVESTITURES (

ACQUISITIONS AND DIVESTITURES (Tables)	12 Months Ended
	Dec. 31, 2019
ACQUISITIONS AND DIVESTITURES [Abstract]
Schedule of purchase price allocation	​ ​ ​ ​ ​ Cash consideration ​ $ 122,861 ​ ​ ​ ​ Fair value of assets acquired: ​ ​ ​ Accounts receivable trade, net ​ $ 30 Prepaid expenses and other ​ ​ 43 Oil and gas properties, successful efforts method: ​ ​ ​ Proved oil and gas properties ​ ​ 106,860 Unproved oil and gas properties ​ ​ 21,769 Total fair value of assets acquired ​ ​ 128,702 ​ ​ ​ ​ Fair value of liabilities assumed: ​ ​ ​ Revenue and royalties payable ​ ​ 3,309 Asset retirement obligations ​ ​ 2,532 Total fair value of liabilities assumed ​ ​ 5,841 ​ ​ ​ ​ Total fair value of assets and liabilities acquired ​ $ 122,861

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2019
LEASES [Abstract]
Summary of lease balance sheet information	Supplemental balance sheet information for the Company’s leases as of December 31, 2019 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Leases ​ Balance Sheet Classification ​ December 31, 2019 ​ ​ ​ ​ ​ ​ Operating Leases ​ ​ ​ ​ ​ Operating lease ROU assets ​ Other long-term assets ​ $ 31,882 Accumulated depreciation ​ Other long-term assets ​ ​ (4,895) Operating lease ROU assets, net ​ ​ ​ $ 26,987 ​ ​ ​ ​ ​ ​ Short-term operating lease obligations ​ Accrued liabilities and other ​ $ 7,346 Long-term operating lease obligations ​ Operating lease obligations ​ ​ 31,722 Total operating lease obligations ​ ​ ​ $ 39,068 ​ ​ ​ ​ ​ ​ Finance Leases ​ ​ ​ ​ ​ Finance lease ROU assets ​ Other property and equipment ​ $ 33,312 Accumulated depreciation ​ Accumulated depreciation, depletion and amortization ​ ​ (14,180) Finance lease ROU assets, net ​ ​ ​ $ 19,132 ​ ​ ​ ​ ​ ​ Short-term finance lease obligations ​ Accrued liabilities and other ​ $ 4,974 Long-term finance lease obligations ​ Other long-term liabilities ​ ​ 16,638 Total finance lease obligations ​ ​ ​ $ 21,612 ​ The Company’s leases have remaining terms of less than one year to 10 years. Most of the Company’s leases do not state or imply a discount rate. Accordingly, the Company uses its incremental borrowing rate based on information available at lease commencement to determine the present value of the lease payments. Information regarding the Company’s lease terms and discount rates as of December 31, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Remaining Lease Term ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 8 years Finance leases ​ ​ ​ ​ 5 years ​ ​ ​ ​ ​ ​ Weighted Average Discount Rate ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 4.6% Finance leases ​ ​ ​ ​ 8.6%
Summary of lease cost	​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2019 Operating lease cost ​ $ 11,512 ​ ​ ​ ​ Finance lease cost: ​ ​ ​ Amortization of ROU assets ​ $ 5,661 Interest on lease liabilities ​ ​ 1,996 Total finance lease cost ​ $ 7,657 ​ ​ ​ ​ Short-term lease payments ​ $ 676,850 Variable lease payments ​ $ 31,812
Summary of lease cash flow information	Supplemental cash flow information related to leases for the year ended December 31, 2019 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash flows from operating leases ​ $ 11,978 Operating cash flows from finance leases ​ $ 2,006 Financing cash flows from finance leases ​ $ 5,140 ​ ​ ​ ​ ROU assets obtained in exchange for new operating lease obligations ​ $ 18,658 ROU assets obtained in exchange for new finance lease obligations ​ $ 4,158
Summary of operating lease obligations	​ The Company’s lease obligations as of December 31, 2019 will mature as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ending December 31, ​ Operating Leases ​ Finance Leases 2020 ​ $ 8,886 ​ $ 6,642 2021 ​ ​ 6,657 ​ ​ 5,753 2022 ​ ​ 5,256 ​ ​ 4,748 2023 ​ ​ 4,592 ​ ​ 3,849 2024 ​ ​ 4,335 ​ ​ 3,246 Remaining ​ ​ 16,951 ​ ​ 2,535 Total lease payments ​ $ 46,677 ​ $ 26,773 Less imputed interest ​ ​ (7,609) ​ ​ (5,161) Total discounted lease payments ​ $ 39,068 ​ $ 21,612
Summary of finance lease obligations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ending December 31, ​ Operating Leases ​ Finance Leases 2020 ​ $ 8,886 ​ $ 6,642 2021 ​ ​ 6,657 ​ ​ 5,753 2022 ​ ​ 5,256 ​ ​ 4,748 2023 ​ ​ 4,592 ​ ​ 3,849 2024 ​ ​ 4,335 ​ ​ 3,246 Remaining ​ ​ 16,951 ​ ​ 2,535 Total lease payments ​ $ 46,677 ​ $ 26,773 Less imputed interest ​ ​ (7,609) ​ ​ (5,161) Total discounted lease payments ​ $ 39,068 ​ $ 21,612
Summary of future lease payments under ASC 840	As of December 31, 2018, minimum future contractual payments for long-term leases under the scope of ASC 840 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pipeline ​ Automobile and ​ ​ Real Estate ​ Transportation ​ Equipment Year ending December 31, ​ Leases ​ Agreement ​ Leases 2019 ​ $ 7,407 ​ $ 3,180 ​ $ 4,216 2020 ​ ​ 4,770 ​ ​ 3,180 ​ ​ 3,422 2021 ​ ​ 4,066 ​ ​ 3,180 ​ ​ 1,678 2022 ​ ​ 4,188 ​ ​ 3,180 ​ ​ 488 2023 ​ ​ 4,017 ​ ​ 3,180 ​ ​ 35 Remaining ​ ​ 25,140 ​ ​ 5,565 ​ ​ - Total lease payments ​ $ 49,588 ​ $ 21,465 ​ $ 9,839

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2019
LONG-TERM DEBT [Abstract]
Schedule of long-term debt	Long-term debt consisted of the following at December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Credit agreement ​ $ 375,000 ​ $ - 1.25% Convertible Senior Notes due 2020 ​ ​ 262,075 ​ ​ 562,075 5.75% Senior Notes due 2021 ​ ​ 773,609 ​ ​ 873,609 6.25% Senior Notes due 2023 ​ ​ 408,296 ​ ​ 408,296 6.625% Senior Notes due 2026 ​ ​ 1,000,000 ​ ​ 1,000,000 Total principal ​ ​ 2,818,980 ​ ​ 2,843,980 Unamortized debt discounts and premiums ​ ​ (2,575) ​ ​ (28,994) Unamortized debt issuance costs on notes ​ ​ (16,520) ​ ​ (22,665) Total long-term debt ​ $ 2,799,885 ​ $ 2,792,321
Schedule of convertible senior notes	The 2020 Convertible Senior Notes consisted of the following at December 31, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 Liability component ​ ​ ​ ​ ​ ​ Principal ​ $ 262,075 ​ $ 562,075 Less: unamortized note discount ​ ​ (2,829) ​ ​ (29,504) Less: unamortized debt issuance costs ​ ​ (220) ​ ​ (2,340) Net carrying value ​ $ 259,026 ​ $ 530,231 Equity component (1) ​ $ 128,452 ​ $ 136,522 (1) Recorded in additional paid-in capital, net of $5 million of issuance costs and $50 million of deferred taxes as of December 31, 2019 and 2018.

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]
Derivative instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average Prices Commodity ​ Settlement Period ​ Index ​ Derivative Instrument ​ Contracted Crude Oil Volumes (Bbl) (1) ​ Swap Price ​ Sub-Floor ​ Floor ​ Ceiling Crude Oil ​ 2020 ​ NYMEX WTI ​ Fixed Price Swaps ​ 4,883,000 ​ $57.57 ​ - ​ - ​ - Crude Oil ​ 2020 ​ NYMEX WTI ​ Two-way Collars ​ 1,648,000 ​ - ​ - ​ $54.33 ​ $61.77 Crude Oil ​ 2020 ​ NYMEX WTI ​ Three-way Collars (2) ​ 3,658,000 ​ - ​ $43.50 ​ $54.00 ​ $63.63 Crude Oil ​ 2021 ​ NYMEX WTI ​ Three-way Collars (2) ​ 1,095,000 ​ - ​ $42.50 ​ $52.50 ​ $59.08 Crude Oil ​ 2021 ​ NYMEX WTI ​ Call Option (3) ​ 365,000 ​ - ​ - ​ - ​ $65.00 ​ ​ ​ ​ ​ ​ Total ​ 11,649,000 ​ ​ ​ ​ ​ ​ ​ ​ (1) Subsequent to December 31, 2019, the Company entered into additional two-way collars for 1,373,000 Bbl of crude oil volumes for the remainder of 2020 and additional three-way collars for 730,000 Bbl of crude oil volumes for 2021. (2) The Company is contracted to pay deferred premiums related to certain three-way collars at each settlement date. The weighted average premium for all three-way collars was $0.56 per Bbl as of December 31, 2019. (3) This derivative instrument is a sold call option.
Schedule of effects of commodity derivative instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss Recognized in Income Not Designated as ​ Statement of Operations ​ Year Ended December 31, ASC 815 Hedges Classification 2019 2018 ​ 2017 Commodity contracts ​ Derivative loss, net ​ $ 53,769 ​ $ 17,170 ​ $ 104,138 Embedded derivatives ​ Loss on sale of properties ​ ​ - ​ ​ - ​ ​ 18,709 Total ​ ​ ​ $ 53,769 ​ $ 17,170 ​ $ 122,847
Location and fair value of derivative instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ Gross ​ ​ ​ ​ Recognized ​ ​ ​ ​ Recognized ​ Gross ​ Fair Value Not Designated as ​ ​ ​ Assets/ ​ Amounts ​ Assets/ ASC 815 Hedges Balance Sheet Classification Liabilities Offset Liabilities Derivative assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Derivative assets ​ $ 75,654 ​ $ (74,768) ​ $ 886 Commodity contracts - non-current ​ Other long-term assets ​ ​ 5,648 ​ ​ (5,648) ​ ​ - Total derivative assets ​ ​ ​ $ 81,302 ​ $ (80,416) ​ $ 886 Derivative liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Accrued liabilities and other ​ $ 85,053 ​ $ (74,768) ​ $ 10,285 Commodity contracts - non-current ​ Other long-term liabilities ​ ​ 6,534 ​ ​ (5,648) ​ ​ 886 Total derivative liabilities ​ ​ ​ $ 91,587 ​ $ (80,416) ​ $ 11,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ Gross ​ ​ ​ ​ Recognized ​ ​ ​ ​ Recognized ​ Gross ​ Fair Value Not Designated as ​ ​ ​ Assets/ ​ Amounts ​ Assets/ ASC 815 Hedges Balance Sheet Classification Liabilities Offset Liabilities Derivative assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Derivative assets ​ $ 69,735 ​ $ (1,393) ​ $ 68,342 Total derivative assets ​ ​ ​ $ 69,735 ​ $ (1,393) ​ $ 68,342 Derivative liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts - current ​ Accrued liabilities and other ​ $ 1,393 ​ $ (1,393) ​ $ - Total derivative liabilities ​ ​ ​ $ 1,393 ​ $ (1,393) ​ $ - (1) Because counterparties to the Company’s financial derivative contracts subject to master netting arrangements are lenders under Whiting Oil and Gas’ credit agreement, which eliminates its need to post or receive collateral associated with its derivative positions, columns for cash collateral pledged or received have not been presented in these tables.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
FAIR VALUE MEASUREMENTS [Abstract]
Summary of the fair values and carrying value of debt instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ December 31, 2018 ​ ​ Fair ​ Carrying ​ Fair ​ Carrying ​ Value (1) Value (2) Value (1) Value (2) 1.25% Convertible Senior Notes due 2020 ​ $ 260,214 ​ $ 259,026 ​ $ 531,161 ​ $ 530,231 5.75% Senior Notes due 2021 ​ ​ 732,995 ​ ​ 772,080 ​ ​ 829,929 ​ ​ 870,545 6.25% Senior Notes due 2023 ​ ​ 343,989 ​ ​ 405,392 ​ ​ 375,632 ​ ​ 404,659 6.625% Senior Notes due 2026 ​ ​ 681,250 ​ ​ 988,387 ​ ​ 865,000 ​ ​ 986,886 Total ​ $ 2,018,448 ​ $ 2,424,885 ​ $ 2,601,722 ​ $ 2,792,321 (1) Fair values are based on quoted market prices for these debt securities, and such fair values are therefore designated as Level 1 within the valuation hierarchy. (2) Carrying values are presented net of unamortized debt issuance costs and debt discounts or premiums.
Fair value assets and liabilities measured on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fair Value ​ Level 1 Level 2 Level 3 December 31, 2019 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 886 ​ $ - ​ $ 886 Total financial assets ​ $ - ​ $ 886 ​ $ - ​ $ 886 Financial Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 10,285 ​ $ - ​ $ 10,285 Commodity derivatives – non-current ​ ​ - ​ ​ 886 ​ ​ - ​ ​ 886 Total financial liabilities ​ $ - ​ $ 11,171 ​ $ - ​ $ 11,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fair Value ​ Level 1 Level 2 Level 3 December 31, 2018 Financial Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity derivatives – current ​ $ - ​ $ 68,342 ​ $ - ​ $ 68,342 Total financial assets ​ $ - ​ $ 68,342 ​ $ - ​ $ 68,342
Reconciliation of changes in the fair value of financial assets (liabilities) designated as Level 3 in the valuation hierarchy	​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2018 Fair value liability, beginning of period ​ $ (63,278) Unrealized gains on commodity derivative contracts included in earnings (1) ​ ​ 2,242 Settlement of commodity derivative contracts ​ ​ 61,036 Transfers into (out of) Level 3 ​ ​ - Fair value liability, end of period ​ $ - (1) Included in derivative loss, net in the consolidated statements of operations.
Non-financial assets and liabilities measured at fair value on a nonrecurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss (Before ​ ​ Net Carrying ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Tax) Year ​ ​ Value as of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ended ​ ​ December 31, ​ Fair Value Measurements Using ​ December 31, ​ 2017 Level 1 Level 2 Level 3 2017 Proved property (1) ​ $ 389,390 ​ $ - ​ $ - ​ $ 389,390 ​ $ 834,950 (1) During the fourth quarter of 2017, proved oil and gas properties at the Redtail field in the Denver-Julesburg Basin (the “DJ Basin”) in Weld County, Colorado, with a previous carrying amount of $1.2 billion were written down to their fair value as of December 31, 2017 of $389 million, resulting in a non-cash impairment charge of $835 million which was recorded within exploration and impairment expense.

SHAREHOLDERS' EQUITY AND NONC_2

SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST (Tables)	12 Months Ended
	Dec. 31, 2019
SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST [Abstract]
Schedule of noncontrolling interest	​ ​ ​ ​ ​ ​ ​ Year Ended ​ December 31, 2017 Balance at beginning of period ​ $ 7,962 Net loss ​ ​ (14) Conveyance of ownership interest ​ ​ (7,948) Balance at end of period ​ $ -

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	12 Months Ended
	Dec. 31, 2019
REVENUE RECOGNITION [Abstract]
Summary of revenue disaggregation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2019 2018 OPERATING REVENUES ​ ​ ​ ​ ​ ​ Oil sales ​ $ 1,492,218 ​ $ 1,850,052 NGL and natural gas sales ​ ​ 80,027 ​ ​ 231,362 Oil, NGL and natural gas sales ​ $ 1,572,245 ​ $ 2,081,414

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2019
STOCK-BASED COMPENSATION [Abstract]
Assumption for valuing market based restricted shares	​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 2018 ​ 2017 Number of simulations 2,500,000 2,500,000 ​ 2,500,000 Expected volatility 72.95% ​ 72.80% ​ 82.44% Risk-free interest rate 2.60% ​ 2.12% ​ 1.52% Dividend yield — — ​ —
Summary of nonvested shares	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Awards ​ Weighted Average ​ ​ Service ‑ Based ​ Market-Based ​ Grant Date ​ RSAs & RSUs PSAs & PSUs Fair Value Nonvested awards, January 1 554,527 503,696 ​ $ 34.94 Granted 467,055 347,493 ​ 24.61 Vested (383,908) (98,581) ​ 32.15 Forfeited (170,172) (304,221) ​ 32.88 Nonvested awards, December 31 467,502 448,387 ​ $ 28.28
Summary of stock options outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ Weighted ​ Aggregate ​ Remaining ​ ​ ​ ​ Average ​ Intrinsic ​ Contractual ​ ​ Number of ​ Exercise Price ​ Value ​ Term ​ Options per Share (in thousands) (in years) Options outstanding at January 1 49,230 ​ $ 195.92 ​ Granted - ​ - ​ Exercised - ​ - ​ $ - Forfeited or expired (6,270) ​ 216.78 ​ Options outstanding at December 31 42,960 ​ $ 192.88 ​ $ - 2.2 Options vested at December 31 42,960 ​ $ 192.88 ​ $ - 2.2 Options exercisable at December 31 42,960 ​ $ 192.88 ​ $ - 2.2

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
INCOME TAXES [Abstract]
Schedule of income tax expense	Income tax expense (benefit) consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 Current income tax expense (benefit) ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ - ​ $ - ​ $ (7,305) State ​ ​ - ​ ​ - ​ ​ 14 Total current income tax benefit ​ ​ - ​ ​ - ​ ​ (7,291) Deferred income tax expense (benefit) ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ 2,140 ​ ​ (10,960) ​ ​ (398,686) State ​ ​ (3,513) ​ ​ 12,333 ​ ​ (77,002) Foreign ​ ​ 73,593 ​ ​ - ​ ​ - Total deferred income tax expense (benefit) ​ ​ 72,220 ​ ​ 1,373 ​ ​ (475,688) Total ​ $ 72,220 ​ $ 1,373 ​ $ (482,979)
Reconciliation of statutory income tax expense to income tax expense	Income tax expense (benefit) differed from amounts that would result from applying the U.S. statutory income tax rate (21% for the years ended December 31, 2019 and 2018 and 35% for the year ended December 31, 2017) to income before income taxes as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 U.S. statutory income tax expense (benefit) ​ $ (35,479) ​ $ 72,211 ​ $ (602,219) State income taxes, net of federal benefit ​ ​ (8,288) ​ ​ 14,324 ​ ​ (39,557) Foreign tax expense ​ ​ (147) ​ ​ - ​ ​ - Valuation allowance ​ ​ 39,672 ​ ​ (87,774) ​ ​ 120,880 Federal tax reform ​ ​ - ​ ​ - ​ ​ (42,033) Impairment charge after enactment of federal tax reform ​ ​ - ​ ​ - ​ ​ 114,293 IRC Section 382 limitation ​ ​ - ​ ​ - ​ ​ (45,899) Market-based equity awards ​ ​ 910 ​ ​ 2,215 ​ ​ 7,003 Outside basis difference recognition ​ ​ 73,740 ​ ​ - ​ ​ - Other ​ ​ 1,812 ​ ​ 397 ​ ​ 4,553 Total ​ $ 72,220 ​ $ 1,373 ​ $ (482,979)
Components of deferred income tax assets and liabilities	The principal components of the Company’s deferred income tax assets and liabilities at December 31, 2019 and 2018 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 Deferred income tax assets ​ ​ ​ ​ ​ ​ Net operating loss carryforward ​ $ 944,709 ​ $ 873,646 Derivative instruments ​ ​ 2,451 ​ ​ - Asset retirement obligations ​ ​ 32,152 ​ ​ 32,546 Restricted stock compensation ​ ​ 2,033 ​ ​ 5,603 EOR credit carryforwards ​ ​ 7,946 ​ ​ 7,946 Lease obligations ​ ​ 14,463 ​ ​ - Other ​ ​ 12,847 ​ ​ 10,777 Total deferred income tax assets ​ ​ 1,016,601 ​ ​ 930,518 Less valuation allowance ​ ​ (188,281) ​ ​ (152,035) Net deferred income tax assets ​ ​ 828,320 ​ ​ 778,483 Deferred income tax liabilities ​ ​ ​ ​ ​ ​ Oil and gas properties ​ ​ 805,989 ​ ​ 740,933 Trust distributions ​ ​ 10,517 ​ ​ 15,479 Lease assets ​ ​ 10,993 ​ ​ - Derivative instruments ​ ​ - ​ ​ 16,375 Discount on convertible senior notes ​ ​ 674 ​ ​ 7,069 Foreign outside basis difference ​ ​ 73,740 ​ ​ - Total deferred income tax liabilities ​ ​ 901,913 ​ ​ 779,856 Total net deferred income tax liabilities ​ $ 73,593 ​ $ 1,373

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
EARNINGS PER SHARE [Abstract]
Reconciliations between basic and diluted earnings per share	The reconciliations between basic and diluted earnings (loss) per share are as follows (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 ​ 2017 Basic Earnings (Loss) Per Share ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common shareholders ​ $ (241,166) ​ $ 342,494 ​ $ (1,237,648) Weighted average shares outstanding, basic ​ ​ 91,285 ​ ​ 90,953 ​ ​ 90,683 Earnings (loss) per common share, basic ​ $ (2.64) ​ $ 3.77 ​ $ (13.65) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted Earnings (Loss) Per Share ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common shareholders ​ $ (241,166) ​ $ 342,494 ​ $ (1,237,648) Weighted average shares outstanding, basic ​ ​ 91,285 ​ ​ 90,953 ​ ​ 90,683 Service-based awards, market-based awards and stock options ​ ​ - ​ ​ 916 ​ ​ - Weighted average shares outstanding, diluted ​ ​ 91,285 ​ ​ 91,869 ​ ​ 90,683 Earnings (loss) per common share, diluted ​ $ (2.64) ​ $ 3.73 ​ $ (13.65)

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2019
COMMITMENTS AND CONTINGENCIES [Abstract]
Minimum future payments under non-cancelable unconditional purchase obligations	The table below shows the Company’s minimum future payments due by period under unconditional purchase obligations as of December 31, 2019 (in thousands): ​ ​ ​ ​ ​ ​ Pipeline ​ ​ Transportation Year ending December 31, ​ Agreements 2020 ​ $ 2,189 2021 ​ ​ 2,189 2022 ​ ​ 2,189 2023 ​ ​ 2,189 2024 ​ ​ 547 Total payments ​ $ 9,303

CAPITALIZED EXPLORATORY WELL _2

CAPITALIZED EXPLORATORY WELL COSTS (Tables)	12 Months Ended
	Dec. 31, 2019
CAPITALIZED EXPLORATORY WELL COSTS [Abstract]
Net changes in capitalized exploratory well costs	Exploratory well costs that are incurred and expensed in the same annual period have not been included in the table below. The net changes in capitalized exploratory well costs were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2019 2018 2017 Beginning balance at January 1 ​ $ - ​ $ 13,894 ​ $ - Additions to capitalized exploratory well costs pending the determination of proved reserves ​ ​ - ​ ​ 10,831 ​ ​ 13,894 Reclassifications to wells, facilities and equipment based on the determination of proved reserves ​ ​ - ​ ​ (24,725) ​ ​ - Ending balance at December 31 ​ $ - ​ $ - ​ $ 13,894

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative I) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Oil and gas receivables collection period	2 months
Allowance for doubtful account	$ 9	$ 12
Materials and supplies inventories	39	23
Oil in tanks	6	5
Impairment of Proved Properties			$ 835
Impairment of Unproved Properties	$ 9	$ 37	$ 59
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	30 years
Furniture and Fixtures [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	4 years
Buildings [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	4 years
Buildings [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	30 years
Leasehold Improvements [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	4 years
Leasehold Improvements [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	30 years
Office Equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Office Equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	30 years
Automobiles [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Automobiles [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	30 years

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative II) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)segmentshares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Summary Of Significant Accounting Policies [Line Items]
Employer's contribution in employees retirement plan | $	$ 7	$ 7	$ 8
Employees vest in employer contribution Percentage, per year of completed service	20.00%
Service period	5 years
Number of operating segments | segment	1
Whiting USA Trust II Units [Member]
Summary Of Significant Accounting Policies [Line Items]
Trust units sold to the public (in shares) | shares	18,400,000

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Credit risk) (Details) - item	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Credit Concentration Risk [Member] | Oil And Gas Sales [Member] | Tesoro Crude Oil Co [Member]
Concentration Risk [Line Items]
Sales as percentage of oil and gas revenue	14.00%	14.00%	18.00%
Credit Concentration Risk [Member] | Oil And Gas Sales [Member] | Philips 66 Company [Member]
Concentration Risk [Line Items]
Sales as percentage of oil and gas revenue	12.00%	11.00%
Credit Concentration Risk [Member] | Oil And Gas Sales [Member] | United Energy Trading, LLC [Member]
Concentration Risk [Line Items]
Sales as percentage of oil and gas revenue		17.00%
Commodity Price Risk [Member] | Derivative Contracts [Member]
Concentration Risk [Line Items]
Number of counterparties	9
Commodity Price Risk [Member] | Derivative Contracts [Member] | Capital One, N. A. [Member]
Concentration Risk [Line Items]
Outstanding derivative contracts as percentage of crude oil volumes hedged	28.00%
Commodity Price Risk [Member] | Derivative Contracts [Member] | JP Morgan Chase [Member]
Concentration Risk [Line Items]
Outstanding derivative contracts as percentage of crude oil volumes hedged	16.00%
Commodity Price Risk [Member] | Derivative Contracts [Member] | Bank of Nova Scotia [Member]
Concentration Risk [Line Items]
Outstanding derivative contracts as percentage of crude oil volumes hedged	14.00%
Commodity Price Risk [Member] | Derivative Contracts [Member] | Merrill Lynch Commodities, Inc. [Member]
Concentration Risk [Line Items]
Outstanding derivative contracts as percentage of crude oil volumes hedged	13.00%
Commodity Price Risk [Member] | Derivative Contracts [Member] | Citibank, N.A. [Member]
Concentration Risk [Line Items]
Outstanding derivative contracts as percentage of crude oil volumes hedged	11.00%

OIL AND GAS PROPERTIES (Details

OIL AND GAS PROPERTIES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
OIL AND GAS PROPERTIES [Abstract]
Costs of completed wells and facilities	$ 9,847,159	$ 9,182,384
Proved leasehold costs	2,702,236	2,729,593
Wells and facilities in progress	159,334	160,995
Unproved leasehold costs	103,278	122,687
Total oil and gas properties, successful efforts method	12,812,007	12,195,659
Accumulated depletion	(5,656,929)	(4,937,579)
Oil and gas properties, net	$ 7,155,078	$ 7,258,080

ACQUISITIONS AND DIVESTITURES_2

ACQUISITIONS AND DIVESTITURES (Acquisition) (Details) $ in Thousands	Jul. 31, 2018USD ($)aitem	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Cash consideration		$ 6,031	$ 142,723	$ 21,429
Richland and McKenzie Counties [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 130,000
Net acquisition area (in acres) | a	54,800
Number of wells acquired | item	117
Cash consideration	$ 122,861
Fair value of assets acquired:
Accounts receivable trade, net	30
Prepaid expenses and other	43
Oil and gas properties, successful efforts method:
Proved oil and gas properties	106,860
Unproved oil and gas properties	21,769
Total fair value of assets acquired	128,702
Fair value of liabilities assumed:
Revenue and royalties payable	3,309
Asset retirement obligations	2,532
Total fair value of liabilities assumed	5,841
Total fair value of assets and liabilities acquired	$ 122,861

ACQUISITIONS AND DIVESTITURES_3

ACQUISITIONS AND DIVESTITURES (Divestitures) (Details)	Aug. 15, 2019USD ($)item	Jul. 29, 2019USD ($)item	Sep. 01, 2017USD ($)	Jul. 19, 2017USD ($)	Jan. 31, 2017USD ($)	Jul. 31, 2016USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Dispositions
Proceeds from sale of properties							$ 72,000,000	$ 4,746,000	$ 929,974,000
Embedded derivatives [Member]
Dispositions
Additional proceeds from disposal for specified period for each $0.01 average NYMEX futures is above threshold price per Bbl						$ 100,000
Maximum possible additional proceeds from divestiture of business						$ 100,000,000
Amount received from settled contingent payment				$ 35,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | McKenzie, Mountrail And Williams Counties [Member]
Dispositions
Number of well sold | item		137
Proceeds from sale of properties		$ 27,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Richland County, Montana And Mountrail and Williams Counties [Member]
Dispositions
Number of well sold | item	58
Proceeds from sale of properties	$ 26,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Robinson Lake Gas Processing Plant and Belfield Gas Processing Plant [Member]
Dispositions
Proceeds from sale of properties					$ 375,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Fort Berthold Indian Reservation Area [Member]
Dispositions
Proceeds from sale of properties			$ 500,000,000
Gain (loss) on sale			$ (402,000,000)

LEASES (Details)

LEASES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease, Practical Expedients, Package [true false]	true
Accounting Standards Update 2016-02 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total leased assets		$ 30
Total lease liabilities		$ 36

LEASES (Balance Sheet and Terms

LEASES (Balance Sheet and Terms) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Operating Leases
Operating lease ROU assets	$ 31,882
Operating lease, Accumulated depreciation	(4,895)
Operating lease ROU assets, net	$ 26,987
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent
Short-term operating lease obligations	$ 7,346
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current
Long-term operating lease obligations	$ 31,722
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term operating lease obligations
Total operating lease obligations	$ 39,068
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Long-term operating lease obligations
Finance Leases
Finance lease ROU assets	$ 33,312
Finance lease, Accumulated depreciation	(14,180)
Finance lease ROU assets, net	$ 19,132
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net
Short-term finance lease obligations	$ 4,974
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current
Long-term finance lease obligations	$ 16,638
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent
Total finance lease obligations	$ 21,612
Weighted Average Remaining Lease Term, Operating lease	8 years
Weighted Average Remaining Lease Term, Finance lease	5 years
Weighted Average Discount Rate, Operating lease (as a percent)	4.60%
Weighted Average Discount Rate, Finance lease (as a percent)	8.60%
Minimum [Member]
Finance Leases
Lease remaining term	1 year
Maximum [Member]
Finance Leases
Lease remaining term	10 years

LEASES (Lease cost) (Details)

LEASES (Lease cost) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
LEASES [Abstract]
Operating lease cost	$ 11,512
Amortization of ROU assets	5,661
Interest on lease liabilities	1,996
Total finance lease cost	7,657
Short-term lease payments	676,850
Variable lease payments	$ 31,812

LEASES (Cash flow) (Details)

LEASES (Cash flow) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
LEASES [Abstract]
Operating cash flows from operating leases	$ 11,978
Operating cash flows from finance leases	2,006
Financing cash flows from finance leases	5,140
ROU assets obtained in exchange for new operating lease obligations	18,658
ROU assets obtained in exchange for new financing lease obligations	$ 4,158

LEASES (Obligations) (Details)

LEASES (Obligations) (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating Leases
2020	$ 8,886
2021	6,657
2022	5,256
2023	4,592
2024	4,335
Remaining	16,951
Total lease payments	46,677
Less imputed interest	(7,609)
Total operating lease obligations	39,068
Finance Leases
2020	6,642
2021	5,753
2022	4,748
2023	3,849
2024	3,246
Remaining	2,535
Total lease payments	26,773
Less imputed interest	(5,161)
Total finance lease obligations	21,612
Operating leases not yet commenced	$ 16,000
Operating lease not yet commenced term	9 years

LEASES (ASC 840 Obligations) (D

LEASES (ASC 840 Obligations) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Real Estate Leases [Member]
Minimum future contractual payments
2019		$ 7,407
2020		4,770
2021		4,066
2022		4,188
2023		4,017
Remaining		25,140
Total		49,588
Pipeline Transportation Agreements [Member]
Minimum future contractual payments
2019	$ 2,189	3,180
2020	2,189	3,180
2021	2,189	3,180
2022	2,189	3,180
2023	547	3,180
Remaining		5,565
Total	$ 9,303	21,465
Automobile and Equipment Leases [Member]
Minimum future contractual payments
2019		4,216
2020		3,422
2021		1,678
2022		488
2023		35
Total		$ 9,839

LONG-TERM DEBT (Schedule of lon

LONG-TERM DEBT (Schedule of long-term debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2015
Debt Instrument [Line Items]
Total principal	$ 2,818,980		$ 2,843,980
Unamortized debt discounts and premiums	(2,575)		(28,994)
Unamortized debt issuance costs on notes	(16,520)		(22,665)
Total long-term debt	2,799,885		2,792,321
Credit Agreement [Member]
Debt Instrument [Line Items]
Total principal	375,000
1.25% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Total principal	262,075	$ 262,000	562,075
Unamortized debt issuance costs on notes	$ (220)		(2,340)		$ (25,000)
Interest rate on debt instrument (as a percent)	1.25%				1.25%
5.75% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Total principal	$ 773,609		873,609
Interest rate on debt instrument (as a percent)	5.75%
6.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Total principal	$ 408,296		408,296
Interest rate on debt instrument (as a percent)	6.25%				6.25%
6.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Total principal	$ 1,000,000		$ 1,000,000
Interest rate on debt instrument (as a percent)	6.625%			6.625%

LONG-TERM DEBT (Credit agreemen

LONG-TERM DEBT (Credit agreement) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Oct. 31, 2019	Sep. 13, 2019
Debt Instrument [Line Items]
Outstanding borrowings under credit facility	$ 375
Weighted average interest rate	3.30%
Minimum [Member]
Debt Instrument [Line Items]
Commitment Fee (as a percent)	0.375%
Maximum [Member]
Debt Instrument [Line Items]
Commitment Fee (as a percent)	0.50%
Base Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	0.50%
Base Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	1.50%
Fed Funds Rate [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	0.50%
LIBOR [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	1.00%
Eurodollar [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	1.50%
Eurodollar [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis points added to reference rate (as a percent)	2.50%
Credit Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity of credit facility	$ 2,050	$ 2,250
Maximum aggregate commitments	1,750	$ 1,750
Borrowing capacity of credit facility, net of letter of credit	1,400
Letters of credit borrowings outstanding	2
Portion of line of credit available for issuance of letters of credit	50
Amount of revolving credit agreement available for additional letters of credit under the agreement	48
Retained earnings free from restrictions	$ 0
Minimum consolidated current assets to consolidated current liabilities ratio	1
Total debt to EBITDAX ratio	4
Aggregate principal amount	$ 100
Senior Notes And Senior Convertible Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount	100
Senior Notes 2021 [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 50
Credit Agreement Maturing April 12, 2023 [Member]
Debt Instrument [Line Items]
Maturity period	91 days
Threshold amount of debt			$ 100
Threshold amount of debt (as a percent)			15.00%
Total debt to EBITDAX ratio			3.25

LONG-TERM DEBT (Summary of seni

LONG-TERM DEBT (Summary of senior notes and convertible senior notes) (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2015
Debt Instrument [Line Items]
Carrying value of debt instrument			$ 2,818,980	$ 2,843,980
1.25% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Carrying value of debt instrument		$ 262,000	$ 262,075	562,075
Interest rate on debt instrument (as a percent)			1.25%			1.25%
Percentage of redemption price		99.00%
5.75% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Carrying value of debt instrument			$ 773,609	873,609
Interest rate on debt instrument (as a percent)			5.75%
Percentage of redemption price	95.467%	94.708%
6.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Carrying value of debt instrument			$ 408,296	408,296
Interest rate on debt instrument (as a percent)			6.25%			6.25%
6.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Carrying value of debt instrument			$ 1,000,000	$ 1,000,000
Interest rate on debt instrument (as a percent)			6.625%		6.625%

LONG-TERM DEBT (Senior notes) (

LONG-TERM DEBT (Senior notes) (Details) - USD ($) $ in Thousands, shares in Millions	Feb. 02, 2017	Oct. 31, 2019	Sep. 30, 2019	Jan. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2015	Sep. 30, 2013	Sep. 30, 2010
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt					$ 7,830	$ (31,968)	$ (1,540)
Repurchase of notes					95,279
Total principal					$ 2,818,980	$ 2,843,980
Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount converted into shares								$ 882,000
Number of shares upon settlement of conversion								21.6
5.0% Senior Notes due 2019 [Member]
Debt Instrument [Line Items]
Notes Issued										$ 1,100,000
Interest rate on debt instrument (as a percent)						5.00%				5.00%
Aggregate principal amount converted into shares								$ 139,000
Notes repurchased, principal amount				$ 961,000
Percentage of redemption price				102.976%
Gain (loss) on extinguishment of debt				$ (31,000)
Repurchase of notes				$ 1,000,000
5.75% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Interest rate on debt instrument (as a percent)					5.75%
Aggregate principal amount converted into shares								326,000
Notes repurchased, principal amount		$ 75,000	$ 25,000
Percentage of redemption price		95.467%	94.708%
Gain (loss) on extinguishment of debt		$ 3,000	$ 1,000
Repurchase of notes		$ 72,000	$ 24,000
Total principal					$ 773,609	$ 873,609
5.75% Senior Notes due 2021, Par [Member]
Debt Instrument [Line Items]
Notes Issued										$ 800,000
Interest rate on debt instrument (as a percent)										5.75%
5.75% Senior Notes due 2021, Premium [Member]
Debt Instrument [Line Items]
Notes Issued										$ 400,000
Interest rate on debt instrument (as a percent)										5.75%
Premium as a percentage of par										101.00%
Debt, effective interest rate					5.50%
6.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Notes Issued									$ 750,000
Interest rate on debt instrument (as a percent)					6.25%				6.25%
Aggregate principal amount converted into shares								342,000
Total principal					$ 408,296	408,296
6.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Notes Issued							$ 1,000,000
Interest rate on debt instrument (as a percent)					6.625%		6.625%
Total principal					$ 1,000,000	$ 1,000,000
6.5% Senior Subordinated Notes due 2018 [Member]
Debt Instrument [Line Items]
Notes Issued											$ 350,000
Interest rate on debt instrument (as a percent)							6.50%				6.50%
Aggregate principal amount converted into shares								$ 75,000
Notes repurchased, principal amount	$ 275,000
Percentage of redemption price	100.00%
Gain (loss) on extinguishment of debt	$ (2,000)
Repurchase of notes	$ 281,000

LONG-TERM DEBT (2020 Convertibl

LONG-TERM DEBT (2020 Convertible senior notes) (Details) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)shares
Debt Instrument [Line Items]
Debt finance cost			$ 16,520	$ 22,665
Repurchase of notes			95,279
Gain (loss) on extinguishment of debt			7,830	(31,968)	$ (1,540)
Amortization of debt issuance costs, debt discount and debt premium			28,340	30,700	$ 31,715
Adjustment to equity component of 2020 Convertible Senior Notes			8,070
Carrying value of debt instrument			2,818,980	2,843,980
1.25% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Principal		$ 1,250,000	$ 262,075	562,075
Interest rate on debt instrument (as a percent)		1.25%	1.25%
Net proceeds		$ 1,200,000
Debt finance cost		25,000	$ 220	2,340
Aggregate principal amount converted into shares						$ 688,000
Number of shares upon settlement of conversion | shares						17.8
Repurchase of notes	$ 299,000
Notes repurchased, principal amount	$ 300,000
Percentage of redemption price	99.00%
Gain (loss) on extinguishment of debt	$ 4,000
Non cash charges	7,000
Transaction costs	1,000
Adjustment to equity component of 2020 Convertible Senior Notes	8,000
Equity component of convertible debt, deferred taxes	0
Carrying value of debt instrument	$ 262,000		$ 262,075	562,075
Conversion ratio			0.0064102
Conversion price per $1,000 principal amount of notes | $ / shares			$ 156
Debt, effective interest rate			5.60%
Estimated fair value of Notes		1,000,000
Debt discount		$ 238,000	$ 2,829	$ 29,504

LONG-TERM DEBT (Schedule of con

LONG-TERM DEBT (Schedule of convertible senior notes) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2015
Debt Instrument [Line Items]
Less: unamortized debt issuance costs		$ (16,520)	$ (22,665)
Interest expense		$ 191,047	197,474	$ 191,088
Percentage of owned subsidiaries		100.00%
1.25% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Principal		$ 262,075	562,075		$ 1,250,000
Less: unamortized note discount		(2,829)	(29,504)		(238,000)
Less: unamortized debt issuance costs		(220)	(2,340)		$ (25,000)
Net carrying value		259,026	530,231
Equity component of convertible debt, deferred taxes	$ 0
Interest expense		26,000	29,000	$ 28,000
Equity Component Of Convertible Senior Note [Member]
Debt Instrument [Line Items]
Less: unamortized debt issuance costs		(5,000)	(5,000)
Equity component		128,452	136,522
Equity component of convertible debt, deferred taxes		$ 50,000	$ 50,000

ASSET RETIREMENT OBLIGATIONS (D

ASSET RETIREMENT OBLIGATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligations
Asset retirement obligations, current portion	$ 4,000	$ 4,000
Reconciliation of the Company's asset retirement obligations
Balance at the beginning of the period	135,834	134,237
Additional liability incurred	2,097	11,981
Revisions to estimated cash flows	(10,945)	(17,197)
Accretion expense	11,602	11,405
Obligations on sold properties	(2,078)	(676)
Liabilities settled	(1,617)	(3,916)
Balance at the end of the period	$ 134,893	$ 135,834

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Derivative instruments) (Details) - Crude Oil [Member]	12 Months Ended
	Dec. 31, 2019bbl$ / bbl	Feb. 27, 2020$ / bbl
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	11,649,000
Fixed Price Swaps [Member] | 2020 [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	4,883,000
Derivative, Swap Price (in dollars per Bbl)	57.57
Two-way Collars [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl)		1,373,000
Two-way Collars [Member] | 2020 [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	1,648,000
Derivative, Floor Price (in dollars per Bbl)	54.33
Derivative, Ceiling Price (in dollars per Bbl)	61.77
Three-way collars [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl)		730,000
Weighted average premium (in dollars per Bbl)	0.56
Three-way collars [Member] | 2020 [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	3,658,000
Derivative, Sub-Floor Price (in dollars per Bbl)	43.50
Derivative, Floor Price (in dollars per Bbl)	54
Derivative, Ceiling Price (in dollars per Bbl)	63.63
Three-way collars [Member] | 2021 [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	1,095,000
Derivative, Sub-Floor Price (in dollars per Bbl)	42.50
Derivative, Floor Price (in dollars per Bbl)	52.50
Derivative, Ceiling Price (in dollars per Bbl)	59.08
Call Option [Member] | 2021 [Member]
Derivative Financial Instruments [Line Items]
Aggregate notional amount of price risk derivatives (in Bbl) | bbl	365,000
Derivative, Ceiling Price (in dollars per Bbl)	65

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Narrative) (Details)	Feb. 01, 2018USD ($)	Jul. 19, 2017USD ($)	Jul. 31, 2016USD ($)$ / bbl	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)
Derivative Financial Instruments [Line Items]
Payment to settle future minimum volume commitments				$ 61,036,000
Embedded derivatives [Member]
Derivative Financial Instruments [Line Items]
Fair value of embedded derivative asset				$ 0	$ 0
Additional proceeds from disposal for specified period for each $0.01 average NYMEX futures is above threshold price per Bbl			$ 100,000
Incremental price per Bbl threshold for additional proceeds from sale | $ / bbl			0.01
Maximum possible additional proceeds from divestiture of business			$ 100,000,000
Amount received from settled contingent payment		$ 35,000,000
Embedded derivatives [Member] | North Ward Estes Properties [Member]
Derivative Financial Instruments [Line Items]
Average price per Bbl threshold for additional proceeds from sale | $ / bbl			50
Crude Oil Sales And Delivery Contract [Member]
Derivative Financial Instruments [Line Items]
Derivative liability	$ 0
Payment to settle future minimum volume commitments	$ 61,000,000

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Effects of commodity derivative instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Financial Instruments [Line Items]
Loss Recognized in Income	$ 53,769	$ 17,170	$ 122,847
Not Designated as ASC 815 Hedges [Member]
Derivative Financial Instruments [Line Items]
Loss Recognized in Income	53,769	17,170	122,847
Commodity contracts [Member] | Not Designated as ASC 815 Hedges [Member]
Derivative Financial Instruments [Line Items]
Loss Recognized in Income	$ 53,769	$ 17,170	104,138
Embedded derivatives [Member] | Not Designated as ASC 815 Hedges [Member]
Derivative Financial Instruments [Line Items]
Loss Recognized in Income			$ 18,709

DERIVATIVE FINANCIAL INSTRUME_6

DERIVATIVE FINANCIAL INSTRUMENTS (Location and fair value of asset derivatives) (Details) - Not Designated as ASC 815 Hedges [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Gross amounts of derivative assets and gross amounts offset [Line Items]
Gross Amounts of Recognized Assets	$ 81,302	$ 69,735
Gross Amounts Offset	(80,416)	(1,393)
Total financial assets	886	68,342
Commodity contracts [Member] | Derivative Assets [Member]
Gross amounts of derivative assets and gross amounts offset [Line Items]
Gross Amounts of Recognized Assets	75,654	69,735
Gross Amounts Offset	(74,768)	(1,393)
Total financial assets	886	$ 68,342
Commodity contracts [Member] | Other Long Term Assets [Member]
Gross amounts of derivative assets and gross amounts offset [Line Items]
Gross Amounts of Recognized Assets	5,648
Gross Amounts Offset	$ (5,648)

DERIVATIVE FINANCIAL INSTRUME_7

DERIVATIVE FINANCIAL INSTRUMENTS (Location and fair value of liability derivatives) (Details) - Not Designated as ASC 815 Hedges [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Gross amounts of derivative liabilities and gross amounts offset [Line Items]
Gross Amounts of Recognized Liabilities	$ 91,587	$ 1,393
Gross Amounts Offset	(80,416)	(1,393)
Total financial liabilities	11,171
Commodity contracts [Member] | Accrued liabilities and other [Member]
Gross amounts of derivative liabilities and gross amounts offset [Line Items]
Gross Amounts of Recognized Liabilities	85,053	1,393
Gross Amounts Offset	(74,768)	$ (1,393)
Total financial liabilities	10,285
Commodity contracts [Member] | Other long-term assets [Member]
Gross amounts of derivative liabilities and gross amounts offset [Line Items]
Gross Amounts of Recognized Liabilities	6,534
Gross Amounts Offset	(5,648)
Total financial liabilities	$ 886

FAIR VALUE MEASUREMENTS (Summar

FAIR VALUE MEASUREMENTS (Summary of the Fair values and carrying value of debt instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2015
Fair Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 2,018,448	$ 2,601,722
Carrying Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 2,424,885	2,792,321
1.25% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure				$ 1,000,000
Interest Rate (as a percent)	1.25%			1.25%
1.25% Convertible Senior Notes due 2020 [Member] | Fair Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 260,214	531,161
1.25% Convertible Senior Notes due 2020 [Member] | Carrying Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 259,026	530,231
5.75% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Interest Rate (as a percent)	5.75%
5.75% Senior Notes due 2021 [Member] | Fair Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 732,995	829,929
5.75% Senior Notes due 2021 [Member] | Carrying Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 772,080	870,545
6.25% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Interest Rate (as a percent)	6.25%			6.25%
6.25% Senior Notes due 2023 [Member] | Fair Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 343,989	375,632
6.25% Senior Notes due 2023 [Member] | Carrying Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 405,392	404,659
6.625% Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Interest Rate (as a percent)	6.625%		6.625%
6.625% Senior Notes due 2026 [Member] | Fair Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 681,250	865,000
6.625% Senior Notes due 2026 [Member] | Carrying Value [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 988,387	$ 986,886

FAIR VALUE MEASUREMENTS (Fair v

FAIR VALUE MEASUREMENTS (Fair value assets and liabilities measured on a recurring basis) (Details) - Recurring Basis [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial Assets
Total financial assets	$ 886	$ 68,342
Financial Liabilities
Total financial liabilities	11,171
Commodity contracts [Member]
Financial Assets
Financial assets - current	886	68,342
Financial Liabilities
Financial liabilities - current	10,285
Financial liabilities - non-current	886
Level 2 [Member]
Financial Assets
Total financial assets	886	68,342
Financial Liabilities
Total financial liabilities	11,171
Level 2 [Member] | Commodity contracts [Member]
Financial Assets
Financial assets - current	886	$ 68,342
Financial Liabilities
Financial liabilities - current	10,285
Financial liabilities - non-current	$ 886

FAIR VALUE MEASUREMENTS (Narrat

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($) $ in Thousands	Feb. 01, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payment to settle future minimum volume commitments		$ 61,036
Crude Oil Sales And Delivery Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payment to settle future minimum volume commitments	$ 61,000

FAIR VALUE MEASUREMENTS (Reconc

FAIR VALUE MEASUREMENTS (Reconciliation-Level 3) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Reconciliation of changes in the fair value of financial assets (liabilities) designated as Level 3 in the valuation hierarchy
Fair value derivative, beginning of period	$ (63,278)
Unrealized gains on commodity derivative contracts included in earnings	2,242
Settlement of commodity derivative contracts	$ 61,036

FAIR VALUE MEASUREMENTS (Non-fi

FAIR VALUE MEASUREMENTS (Non-financial assets and liabilities measured at fair value on a nonrecurring basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-recurring assets at fair value, impairment loss (before tax)			$ 835,000
Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-recurring assets at fair value, impairment loss (before tax)	$ 0	$ 0
Nonrecurring [Member] | Proved Properties [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Proved property			389,390	$ 1,200,000
Non-recurring assets at fair value, impairment loss (before tax)			834,950
Nonrecurring [Member] | Proved Properties [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Proved property			$ 389,390

SHAREHOLDERS' EQUITY AND NONC_3

SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST (Narrative) (Details)	Nov. 08, 2017shares	Nov. 30, 2017	Dec. 31, 2019shares	Dec. 31, 2018shares	Nov. 07, 2017shares
SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST [Abstract]
Reverse stock split ratio	0.25	0.25
Common stock, shares authorized	225,000,000		225,000,000	225,000,000	600,000,000

SHAREHOLDERS' EQUITY AND NONC_4

SHAREHOLDERS' EQUITY AND NONCONTROLLING INTEREST (Schedule of noncontrolling interest) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017
Noncontrolling Interest disclosures [Line Items]
Balance at beginning of period	$ 7,962
Net loss	(14)
Conveyance of ownership interest	$ (7,948)
Sustainable Water Resources, LLC [Member]
Noncontrolling Interest disclosures [Line Items]
Third party ownership interest (as a percent)		25.00%

REVENUE RECOGNITION (Revenue Re

REVENUE RECOGNITION (Revenue Reclassification) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 1,572,245	$ 2,081,414	$ 1,481,435
Oil sales [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	1,492,218	1,850,052
NGL and natural gas sales [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 80,027	$ 231,362

REVENUE RECOGNITION (Narrative)

REVENUE RECOGNITION (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition [Line Items]
Receivable balance	$ 161	$ 165
Revenue, Practical Expedient, Initial Application and Transition, Nondisclosure of Transaction Price Allocation to Remaining Performance Obligation [true false]	true
Minimum [Member]
Revenue Recognition [Line Items]
Payment received for product sales, period	1 month
Maximum [Member]
Revenue Recognition [Line Items]
Payment received for product sales, period	3 months

STOCK-BASED COMPENSATION (Narra

STOCK-BASED COMPENSATION (Narrative) (Details) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2019shares	Dec. 31, 2019USD ($)item$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)item$ / sharesshares	Dec. 31, 2016shares	Dec. 31, 2013shares
Share-based compensation disclosures [Line Items]
Number of shares authorized upon shareholder's approval						1,325,000
Number of additional shares authorized	3,000,000				1,375,000
Number of shares available for grant		3,698,933
Granted (in dollars per share) | $ / shares		$ 24.61
Unrecognized compensation cost, restricted stock | $		$ 13
Weighted average period over which cost will be recognized		2 years
Total fair value of restricted stock vested | $		$ 12	$ 16	$ 15
Stock compensation expense | $		$ 8	$ 18	$ 22
Stock Option [Member]
Share-based compensation disclosures [Line Items]
Maximum number of Shares per employee		500,000
Maximum number of Shares per non-employee		25,000
Stock options granted		0	0	0
Vesting (service) period		3 years
Unrecognized compensation cost, options | $		$ 0
Non Option award [Member]
Share-based compensation disclosures [Line Items]
Maximum number of Shares per employee		500,000
Service-based [Member]
Share-based compensation disclosures [Line Items]
Maximum number of Shares per non-employee		25,000
Granted (in shares)		467,055	249,983	538,194
Granted (in dollars per share) | $ / shares		$ 24.65	$ 32.34	$ 40.66
Service-based [Member] | Share-based Payment Arrangement, Employee [Member]
Share-based compensation disclosures [Line Items]
Vesting (service) period		3 years
RSA [Member] | Share-based Payment Arrangement, Nonemployee [Member]
Share-based compensation disclosures [Line Items]
Vesting (service) period		1 year
RSU [Member]
Share-based compensation disclosures [Line Items]
Granted (in shares)		774,665	308,432
Market-based [Member]
Share-based compensation disclosures [Line Items]
Vesting (service) period		3 years
Granted (in shares)		347,493	230,932
Granted (in dollars per share) | $ / shares		$ 25.97	$ 27.28	$ 63.04
Target share granted percent, will be share-settled		100.00%
Market-based [Member] | Minimum [Member]
Share-based compensation disclosures [Line Items]
Possible multiplier of shares earned | item		0
Market-based [Member] | Maximum [Member]
Share-based compensation disclosures [Line Items]
Possible multiplier of shares earned | item		2
PSA [Member]
Share-based compensation disclosures [Line Items]
Vesting (service) period		3 years
Granted (in shares)				168,466
PSA [Member] | Minimum [Member]
Share-based compensation disclosures [Line Items]
Possible multiplier of shares earned | item				0
PSA [Member] | Maximum [Member]
Share-based compensation disclosures [Line Items]
Possible multiplier of shares earned | item				2
PSU [Member]
Share-based compensation disclosures [Line Items]
Vesting (service) period		3 years

STOCK-BASED COMPENSATION (Assum

STOCK-BASED COMPENSATION (Assumptions) (Details) - Market-based [Member] - item	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of simulations	2,500,000	2,500,000	2,500,000
Expected volatility (as a percent)	72.95%	72.80%	82.44%
Risk-free interest rate (as a percent)	2.60%	2.12%	1.52%
Dividend yield (as a percent)	0.00%	0.00%	0.00%

STOCK-BASED COMPENSATION (Summa

STOCK-BASED COMPENSATION (Summary of nonvested awards) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at the beginning of the period (in dollars per share)	$ 34.94
Granted (in dollars per share)	24.61
Vested (in dollars per share)	32.15
Forfeited (in dollars per share)	32.88
Balance at the end of the period (in dollars per share)	$ 28.28	$ 34.94
Service-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at the beginning of the period (in shares)	554,527
Granted (in shares)	467,055	249,983	538,194
Vested (in shares)	(383,908)
Forfeited (in shares)	(170,172)
Balance at the end of the period (in shares)	467,502	554,527
Granted (in dollars per share)	$ 24.65	$ 32.34	$ 40.66
Market-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at the beginning of the period (in shares)	503,696
Granted (in shares)	347,493	230,932
Vested (in shares)	(98,581)
Forfeited (in shares)	(304,221)
Balance at the end of the period (in shares)	448,387	503,696
Granted (in dollars per share)	$ 25.97	$ 27.28	$ 63.04

STOCK-BASED COMPENSATION (Sum_2

STOCK-BASED COMPENSATION (Summary of stock options) (Details) - Stock Option [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at the beginning of the period (in shares)	49,230
Granted	0	0	0
Exercised (in shares)	0		0
Forfeited or expired (in shares)	(6,270)
Balance at the end of the period (in shares)	42,960	49,230
Options vested (in shares)	42,960
Options exercisable (in shares)	42,960
Balance at the beginning of the period (in dollars per share)	$ 195.92
Forfeitures or expired (in dollars per share)	216.78
Balance at the end of the period (in dollars per share)	192.88	$ 195.92
Options vested (in dollars per share)	192.88
Options exercisable (in dollars per share)	$ 192.88
Aggregate Intrinsic Value, options Exercised		$ 0.1
Weighted Average Remaining Contractual Term, options outstanding	2 years 2 months 12 days
Weighted Average Remaining Contractual Term, options vested	2 years 2 months 12 days
Weighted Average Remaining Contractual Term, options exercisable	2 years 2 months 12 days

INCOME TAXES (Schedule of incom

INCOME TAXES (Schedule of income expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INCOME TAXES [Abstract]
Federal			$ (7,305)
State			14
Total current income tax benefit			(7,291)
Federal	$ 2,140	$ (10,960)	(398,686)
State	(3,513)	12,333	(77,002)
Foreign	73,593
Total deferred income tax expense (benefit)	72,220	1,373	(475,688)
Total income tax expense (benefit)	$ 72,220	$ 1,373	$ (482,979)

INCOME TAXES (Reconciliation of

INCOME TAXES (Reconciliation of statutory income tax expense to income expense) (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
INCOME TAXES [Abstract]
U.S. statutory income tax rate (as a percent)	21.00%			35.00%	21.00%
U.S. statutory income tax expense (benefit)		$ (35,479)	$ 72,211	$ (602,219)
State income taxes, net of federal benefit		(8,288)	14,324	(39,557)
Foreign tax expense		(147)
Valuation allowance		39,672	(87,774)	120,880
Federal tax reform				(42,033)
Impairment charge after enactment of federal tax reform				114,293
IRC Section 382 limitation				(45,899)
Market-based equity awards		910	2,215	7,003
Outside basis difference recognition		73,740
Other		1,812	397	4,553
Total income tax expense (benefit)		$ 72,220	$ 1,373	$ (482,979)

INCOME TAXES (Components of def

INCOME TAXES (Components of deferred income tax assets and liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES [Abstract]
Net operating loss carryforward	$ 944,709	$ 873,646
Derivative instruments	2,451
Asset retirement obligations	32,152	32,546
Restricted stock compensation	2,033	5,603
EOR credit carryforwards	7,946	7,946
Lease obligations	14,463
Other	12,847	10,777
Total deferred income tax assets	1,016,601	930,518
Less valuation allowances	(188,281)	(152,035)
Net deferred income tax assets	828,320	778,483
Oil and gas properties	805,989	740,933
Trust distributions	10,517	15,479
Lease assets	10,993
Derivative instruments		16,375
Discount on convertible senior notes	674	7,069
Foreign outside basis difference	73,740
Total deferred income tax liabilities	901,913	779,856
Total net deferred income tax liabilities	$ 73,593	$ 1,373

INCOME TAXES (Narrative) (Detai

INCOME TAXES (Narrative) (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Valuation allowance recognized		$ (41,000)		$ 30,000	$ 259,000
Federal operating loss carryforwards			$ 3,400,000			$ 3,400,000
EOR credit carryforwards			$ 7,946	7,946		$ 7,946
U.S. statutory income tax rate (as a percent)	21.00%				35.00%	21.00%
Tax Cut and Jobs Act of 2017, income tax expense, revaluation of deferred tax assets and liabilities					$ 51,000
Tax Cut and Jobs Act of 2017, income tax benefit, reduction in existing valuation allowances					93,000
Tax Cut and Jobs Act of 2017, possible impact, limitation on net operating loss, percentage of taxable income			80.00%
Valuation allowance			$ 188,281	152,035		$ 188,281
Deferred tax liability recognized			73,740			73,740
Unrecognized tax benefits, penalties and interest accrued			0	0	$ 0	0
IRC Section 382 Limitations [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance			138,000	138,000		138,000
EOR Credits [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance			8,000	8,000		8,000
Canadian NOL Carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance				5,000
Short-Term Capital Loss Carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance			1,000	$ 1,000		1,000
General Valuation Allowance [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance			$ 41,000			$ 41,000

EARNINGS PER SHARE (Reconciliat

EARNINGS PER SHARE (Reconciliation) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Nov. 08, 2017	Nov. 30, 2017	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares
Basic Earnings (Loss) Per Share
Net income (loss) attributable to common shareholders | $			$ (241,166)	$ 342,494	$ (1,237,648)
Weighted average shares outstanding, basic			91,285	90,953	90,683
Earnings (loss) per common share, basic (in dollars per share) | $ / shares			$ (2.64)	$ 3.77	$ (13.65)
Diluted Earnings (Loss) Per Share
Service-based awards, market-based awards and stock options				916
Weighted average shares outstanding, diluted			91,285	91,869	90,683
Earnings (loss) per common share, diluted (in dollars per share) | $ / shares			$ (2.64)	$ 3.73	$ (13.65)
Reverse stock split ratio	0.25	0.25

EARNINGS PER SHARE (Narrative)

EARNINGS PER SHARE (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)shares	Dec. 31, 2018shares	Dec. 31, 2017shares
Service Based Restricted Stock [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Antidilutive securities excluded from computation of earnings per share	344,671
Market Based Restricted Stock [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,511
Stock Option [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Antidilutive securities excluded from computation of earnings per share			1,083
Stock options excluded from earnings per share calculation (in shares)	45,588	100,708	123,775
Service-based [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Antidilutive securities excluded from computation of earnings per share			509,744
Market-based [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Antidilutive securities excluded from computation of earnings per share			22,946
Market-based awards excluded from earnings per share calculation (in shares)			345,071
1.25% Convertible Senior Notes due 2020 [Member]
Shares excluded from Earnings Per Share calculation [Line Items]
Debt instrument, convertible, number of common stock | $	1.7

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Minimum future payments) (Details) - Pipeline Transportation Agreements [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Unrecorded Unconditional Purchase Obligation [Line Items]
2020	$ 2,189	$ 3,180
2021	2,189	3,180
2022	2,189	3,180
2023	2,189	3,180
2024	547	3,180
Thereafter		5,565
Total	$ 9,303	$ 21,465

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES (Narrative) (Details) - Pipeline Transportation Agreements [Member] $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of contracts | contract	2
Payments under purchase contracts	$ 2	$ 2	$ 2
Future estimated commitments	$ 9

COMMITMENTS AND CONTINGENCIES_4

COMMITMENTS AND CONTINGENCIES (Other than unconditional obligations) (Details) MBbls in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)MBblsitemcontractbbl	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Commitments
Damages being sought	$ 41
Take-Or-Pay Agreements [Member]
Commitments
Future estimated commitments	8
Payments under purchase contracts	8	$ 8	$ 22
Deficiency payments	8	2
Water Disposal Agreement [Member]
Commitments
Future estimated commitments	83
Payments under purchase contracts	20	19	16
Deficiency payments	$ 14	5	4
Crude Oil Sales And Delivery Contract [Member]
Commitments
Number of contracts | contract	3
Crude Oil Sales And Delivery Contract [Member] | Mountrail County, North Dakota [Member]
Commitments
Number of contracts | item	1
Delivery commitments, volume per day | MBbls	15
Agreement term	7 years
Crude Oil Sales And Delivery Contract [Member] | Weld County, Colorado [Member]
Commitments
Deficiency payments	$ 64	$ 39	$ 66
Delivery commitments for next year | bbl	4,100
Crude Oil Sales And Delivery Contract [Member] | Williston Basin [Member]
Commitments
Delivery commitments, volume per day | MBbls	10
Agreement term	7 years

CAPITALIZED EXPLORATORY WELL _3

CAPITALIZED EXPLORATORY WELL COSTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
CAPITALIZED EXPLORATORY WELL COSTS [Abstract]
Balance at the beginning of the period	$ 13,894
Additions to capitalized exploratory well costs pending the determination of proved reserves	10,831	$ 13,894
Reclassifications to wells, facilities and equipment based on the determination of proved reserves	$ (24,725)
Balance at the end of the period		$ 13,894
Capitalized exploratory cost for exploratory wells in progress			$ 0

RESTRUCTURING (Details)

RESTRUCTURING (Details) $ in Millions	1 Months Ended
	Jul. 31, 2019USD ($)
One-time employee termination benefits [Member]
Restructuring
Restructuring costs incurred	$ 8

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) $ in Thousands	Jan. 09, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Subsequent Event [Line Items]
Proceeds from sale of properties		$ 72,000	$ 4,746	$ 929,974
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of well sold | item	30
Proceeds from sale of properties	$ 25,000