CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018	[1]
Operating Activities
Net income (loss) including noncontrolling interest		$ (1,262,445)	$ 1,253,302		$ 419,486
Adjustments to reconcile net income (loss) to net cash provided by continuing operations activities:
(Income) loss from discontinued operations		7,151	(1,064,487)		(250,348)
Depreciation, depletion and amortization		987,239	1,147,842		775,614
Previously suspended exploration costs		21,099	12,840		20,508
Amortization of undeveloped leases		26,743	27,973		40,177
Accretion of asset retirement obligations		42,136	40,506		27,119
Impairment of assets		1,206,284	0		20,000
Noncash restructuring expense		17,565	0		0
Deferred income tax charge (benefit)		(278,042)	28,530		(177,627)
Mark to market loss (gain) on contingent consideration		(13,783)	8,672		(4,810)
Mark to market loss (gain) on crude contracts		69,310	33,364		(33,954)
Long-term non-cash compensation		46,558	76,958		72,151
Net (increase) decrease in noncash operating working capital		(32,027)	(16,887)		(16,103)
Other operating activities, net		(35,080)	(59,508)		(142,818)
Net cash provided by continuing operations activities		802,708	1,489,105		749,395
Investing Activities
Property additions and dry hole costs		(759,809)	(1,244,069)		(1,011,292)
Property additions for King's Quay FPS		(112,961)	(100,202)		0
Proceeds from sales of property, plant and equipment		13,750	20,382		1,175
Acquisition of oil and natural gas properties		0	(1,212,315)		(794,623)
Net cash required by investing activities		(859,020)	(2,536,204)		(1,804,740)
Financing Activities
Borrowings on revolving credit facility and term loan		450,000	1,725,000		325,000
Repayment of revolving credit facility and term loan		(250,000)	(2,050,000)		0
Cash dividends paid		(95,989)	(163,669)		(173,044)
Distributions to noncontrolling interest		(43,673)	(128,158)		0
Early retirement of debt		(12,225)	(521,332)		0
Withholding tax on stock-based incentive awards		(7,094)	(6,991)		(8,076)
Debt issuance, net of cost		(613)	542,394		0
Capital lease obligation payments		(695)	(688)		(318)
Loss on early extinguishment of debt		0	(26,626)		0
Repurchase of common stock		0	(499,924)		0
Net cash (required) provided by financing activities		39,711	(1,129,994)		143,562
Cash Flows from Discontinued Operations
Operating activities	[2]	(1,202)	73,783		406,857
Investing activities	[2]	4,494	2,022,034		(91,398)
Financing activities	[2]	0	(4,914)		(9,432)
Net cash provided by discontinued operations	[2]	3,292	2,090,903		306,027
Cash from discontinued operations	[2]	18,438	2,120,397		612,543
Effect of exchange rate changes on cash and cash equivalents		2,009	3,533		28,730
Net increase (decrease) in cash and cash equivalents		3,846	(53,163)		(270,510)
Cash and cash equivalents at beginning of period		306,760	359,923	[1]	630,433
Cash and cash equivalents at end of period		$ 310,606	$ 306,760		$ 359,923

[1] Reclassified to conform with current presentation

[2] Net cash provided by discontinued operations are not part of the cash flow reconciliation.