Supplemental Balance Sheet, Income Statement and Cash Flow Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Investment income (loss)									$ 1,183	$ 2,308	$ 11,831
Impairment and other charges									505,164	368,967	1,005,110
Interest expense									185,360	181,928	177,948
General and administrative expenses									227,639	324,328	500,036
Other expense (income), net									37,509	(39,172)	31,386
Income (loss) from continuing operations before income taxes									(1,198,075)	(427,535)	(604,615)
Tax expense (benefit)									186,831	98,038	(62,666)
Net income (loss)	$ (334,462)	$ (110,026)	$ (187,549)	$ (397,570)	$ (162,820)	$ (296,154)	$ (36,865)	$ 123,545	(1,029,607)	(372,294)	(669,244)
Reclassification adjustment for (gains)/losses included in net income (loss)
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Investment income (loss)											4,635
Impairment and other charges									3,495		6,972
Interest expense									613	613	614
General and administrative expenses									1,061	1,104	303
Other expense (income), net									3,059	5,365
Income (loss) from continuing operations before income taxes									(8,228)	(7,082)	(3,254)
Tax expense (benefit)									1,551	648	(552)
Net income (loss)									$ (6,677)	$ (6,434)	$ (3,806)