Supplemental Balance Sheet and Income Statement Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense	$ 51,291	$ 51,415	$ 155,134	$ 173,393
General and administrative expenses	63,577	66,813	196,159	209,207
Income (loss) from continuing operations before income taxes	(75,885)	(83,221)	(330,865)	(375,200)
Income tax expense (benefit)	23,903	10,489	65,100	57,312
Net income (loss)	(99,631)	(107,643)	(395,999)	(447,104)
Reclassification adjustment for (gains)/losses included in net income (loss)
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense	142	143	424	425
General and administrative expenses	54	54	162	162
Income (loss) from continuing operations before income taxes	(196)	(197)	(586)	(587)
Income tax expense (benefit)	(48)	(48)	(142)	(139)
Net income (loss)	$ (148)	$ (149)	$ (444)	$ (448)