CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		3 Months Ended			9 Months Ended			12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018		Dec. 31, 2018
Operating Activities
Net income including noncontrolling interest		$ 1,111,702	$ 93,943	[1]	$ 1,307,713	$ 307,715	[1],[2]
Adjustments to reconcile net income to net cash provided by continuing operations activities:
(Income) loss from discontinued operations		(953,368)	(37,812)	[1]	(1,027,632)	(186,188)	[1],[2]
Depreciation, depletion and amortization		325,562	197,503	[1]	819,270	570,997	[1],[2]
Previously suspended exploration costs (credits)					12,901	4,514	[2]
Amortization of undeveloped leases					21,680	31,544	[2]
Accretion of asset retirement obligations		10,587	6,466	[1]	29,824	19,234	[1],[2]
Deferred income tax charge (benefit)					50,597	(134,393)	[2]
Pretax (gain) loss from sale of assets					(363)	(6)	[2]
Mark to market and revaluation of contingent consideration					512	0	[2]
Mark to market of crude contracts					(100,076)	1,065	[2]
Long-term non-cash compensation					60,567	52,309	[2]
Net (increase) decrease in noncash operating working capital					40,257	(9,501)	[2]
Other operating activities, net					(62,023)	(55,924)	[2]
Net cash provided by continuing operations activities					1,153,227	601,366	[2]
Investing Activities
Acquisition of oil and gas properties					(1,212,949)	0	[2]
Property additions and dry hole costs					(1,009,146)	(797,630)	[2]
Proceeds from sales of property, plant and equipment					19,072	921	[2]
Net cash required by investing activities					(2,203,023)	(796,709)	[2]
Financing Activities
Borrowings on revolving credit facility and term loan					1,575,000	0
Repayment of revolving credit facility and term loan					(1,900,000)	0
Repurchase of common stock					(405,938)	0	[2]
Capital lease obligation payments					(510)	(154)	[2]
Withholding tax on stock-based incentive awards					(6,991)	(6,922)	[2]
Distribution to noncontrolling interest					(97,510)	0	[2]
Cash dividends paid					(125,437)	(129,780)	[2]
Net cash provided (required) by financing activities					(961,386)	(136,856)	[2]
Cash Flows from Discontinued Operations
Operating activities	[3]				74,361	370,343	[2]
Investing activities	[3]				1,985,202	(60,715)	[2]
Financing activities	[3]				(4,914)	(7,013)	[2]
Net cash provided by discontinued operations	[3]				2,054,649	302,615	[2]
Cash transferred from discontinued operations to continuing operations					2,083,565	536,492	[2]
Effect of exchange rate changes on cash and cash equivalents					2,593	13,107	[2]
Net increase (decrease) in cash and cash equivalents					74,976	217,400	[2]
Cash and cash equivalents at beginning of period					359,923	630,433	[2]	$ 630,433	[2]
Cash and cash equivalents at end of period		$ 434,899	$ 847,833	[2]	$ 434,899	$ 847,833	[2]	$ 359,923

[1] Reclassified to conform to current presentation (see Note A).

[2] Reclassified to conform to current presentation (See Note A).

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