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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Income (loss) from continuing operations before income taxes
United States									$ (299,349)	$ (595,196)		$ (1,259,268)
Foreign									371,151	102,081		(2,022,994)
Income (loss) from continuing operations before income taxes	$ 2,400	$ (63,600)	$ (21,900)	$ 154,900	$ (80,100)	$ (16,700)	$ (131,300)	$ (265,000)	71,802	(493,115)	[1]	(3,282,262)	[1]
Income tax expense (benefit)
Federal - Current												(9,435)
Federal - Deferred									156,065	(197,450)		(241,127)
Total Federal income tax expense (benefit)									156,065	(197,450)		(250,562)
State									4,230	13,984		(5,294)
Foreign - Current									122,318	146,861		(40,550)
Foreign - Deferred									100,125	(182,567)		(730,084)
Total Foreign income tax expense (benefit)									222,443	(35,706)		(770,634)
Total income tax expense (benefit)									$ 382,738	$ (219,172)	[1]	$ (1,026,490)	[1]

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