Supplemental Balance Sheet, Income Statement and Cash Flow Information - Reclass Accumulated Other (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense									$ 206,274	$ 204,311	$ 227,124
General and administrative expenses									203,515	258,731	265,822
Income (loss) from continuing operations before income taxes									(705,567)	(588,922)	(518,794)
Tax expense (benefit)									57,286	91,576	79,269
Net income (loss)	$ (103,879)	$ (146,660)	$ (137,945)	$ (374,362)	$ (284,511)	$ (99,631)	$ (192,835)	$ (103,533)	(762,846)	(680,510)	(612,726)
Reclassification out of Accumulated Other Comprehensive Income
Unrealized (gains) losses on available-for-sale securities that were reclassified from net income
Interest expense									160	567	567
General and administrative expenses									210	217	216
Income (loss) from continuing operations before income taxes									(370)	(784)	(783)
Tax expense (benefit)									(141)	(190)	(187)
Net income (loss)									$ (229)	$ (594)	$ (596)