Supplemental Balance Sheet and Income Statement Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Investment income (loss)	$ (1,342)	$ 373	$ (4,041)	$ 208
Interest expense	51,415	54,607	173,393	165,813
General and administrative expenses	66,813	65,010	209,207	192,114
Other expense (income), net	22,907	5,559	114,597	29,173
Income (loss) from continuing operations before income taxes	(83,221)	(133,994)	(375,200)	(442,203)
Income tax expense (benefit)	10,489	(14,709)	57,312	(59,814)
Net income (loss)	(107,643)	(146,419)	(447,104)	(425,466)
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	143	153	425	459
General and administrative expenses	54	50	162	150
Other expense (income), net				1,341
Income (loss) from continuing operations before income taxes	(197)	(203)	(587)	(1,950)
Income tax expense (benefit)	(48)	(78)	(139)	(235)
Net income (loss)	$ (149)	$ (125)	$ (448)	$ (1,715)