Supplemental Balance Sheet and Income Statement Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Investment income (loss)	$ 2,036	$ 469	$ (1,162)	$ 10,146
Impairments and other charges	57,852	102,570	334,286	99,903
Interest expense	51,206	51,491	105,928	103,843
General and administrative expenses	46,244	64,415	103,628	132,582
Income (loss) from continuing operations before income taxes	(133,522)	(181,403)	(490,098)	(254,980)
Tax expense (benefit)	4,446	11,398	22,139	41,197
Net income (loss)	(137,945)	(192,835)	(512,307)	(296,368)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense	142	142	284	282
General and administrative expenses	52	54	104	108
Income (loss) from continuing operations before income taxes	(194)	(196)	(388)	(390)
Tax expense (benefit)	(47)	(48)	(94)	(94)
Net income (loss)	$ (147)	$ (148)	$ (294)	$ (296)