Supplemental Balance Sheet and Income Statement Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Investment income (loss)	$ (742)	$ (1,437)	$ (1,904)	$ 8,709
Impairments and other charges	5,017	3,629	339,303	106,007
Interest expense	52,403	51,291	158,331	155,134
General and administrative expenses	46,168	63,577	149,796	196,159
Income (loss) from continuing operations before income taxes	(150,377)	(75,885)	(640,475)	(330,865)
Tax expense (benefit)	(3,695)	23,903	18,444	65,100
Net income (loss)	(146,660)	(99,631)	(658,967)	(395,999)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense	(124)	142	160	424
General and administrative expenses	52	54	156	162
Income (loss) from continuing operations before income taxes	72	(196)	(316)	(586)
Tax expense (benefit)	(35)	(48)	(129)	(142)
Net income (loss)	$ 107	$ (148)	$ (187)	$ (444)