Supplemental Balance Sheet and Income Statement Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Impairments and other charges									$ 144,446	$ 44,536	$ 498,499
Interest expense									227,124	222,889	185,360
General and administrative expenses									265,822	251,184	227,639
Other expense (income), net									29,532	14,880	44,174
Income (loss) from continuing operations before income taxes									(518,794)	(580,084)	(1,198,075)
Income tax expense (benefit)									79,269	(82,970)	(186,831)
Net income (loss)	$ (165,622)	$ (107,643)	$ (195,799)	$ (143,662)	$ (115,167)	$ (146,419)	$ (130,980)	$ (148,067)	(612,726)	(540,633)	(1,029,607)
Reclassification adjustment for (gains)/losses included in net income (loss)
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Impairments and other charges										970	3,495
Interest expense									567	613	613
General and administrative expenses									216	200	1,061
Other expense (income), net											3,059
Income (loss) from continuing operations before income taxes									(783)	(1,783)	(8,228)
Income tax expense (benefit)									(187)	(315)	(1,551)
Net income (loss)									$ (596)	$ (1,468)	$ (6,677)