Supplemental Balance Sheet, Income Statement and Cash Flow Information - Reclass Accumulated Other (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
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Impairments and other charges									$ 290,471	$ 144,446	$ 44,536
Interest expense									204,311	227,124	222,889
General and administrative expenses									258,731	265,822	251,184
Income (loss) from continuing operations before income taxes									(588,922)	(518,794)	(580,084)
Tax expense (benefit)									91,576	79,269	(82,970)
Net income (loss)	$ (284,511)	$ (99,631)	$ (192,835)	$ (103,533)	$ (165,622)	$ (107,643)	$ (195,799)	$ (143,662)	(680,510)	(612,726)	(540,633)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Impairments and other charges											970
Interest expense									567	567	613
General and administrative expenses									217	216	200
Income (loss) from continuing operations before income taxes									(784)	(783)	(1,783)
Tax expense (benefit)									(190)	(187)	(315)
Net income (loss)									$ (594)	$ (596)	$ (1,468)