Income Taxes - Components of Income (Loss) from Continuing Operations Before Income Taxes and Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Income (loss) from continuing operations before income taxes
United States									$ 282,199	$ 14,907		$ (299,349)
Foreign									(78,701)	28,095		16,465
Income (loss) from continuing operations before income taxes	$ (115,300)	$ 177,100	$ 107,900	$ 33,700	$ 12,700	$ 74,000	$ (22,600)	$ (21,100)	203,498	43,002	[1]	(282,884)	[1]
Income tax expense (benefit)
U.S. Federal – Current									0	(9,765)		0
Federal - Deferred									30,598	(131,200)		156,065
Total U.S. Federal									30,598	(140,965)		156,065
State									5,139	3,299		4,230
Foreign – Current									(17,823)	61,257		59
Foreign - Deferred									(3,231)	(49,727)		109,777
Total Foreign									(21,054)	11,530		109,836
Total income tax expense (benefit)									$ 14,683	$ (126,136)	[1]	$ 270,131	[1]

[1] ¹ Reclassified to conform with current presentation (see Notes C and E). 2017 revenue is presented net of $58.9 million of transportation, gathering and processing costs as historically shown prior to the adoption of ASC 606 on January 1, 2018. See Notes to Consolidated Financial Statements, page 58.