Unaudited Interim Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Total Equity
Beginning Balance at Dec. 31, 2018		$ 2,500	$ 6,120,436	$ 943,005	$ (324,373)	$ 6,741,568
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital			(245,000)			(245,000)
Comprehensive income:
Net income (loss)	$ (900,024)			(900,024)		(900,024)
Other comprehensive income (loss), net of tax	224,777				224,777	224,777
Total comprehensive income (loss)						(675,247)
Ending Balance at Mar. 31, 2019		2,500	5,875,436	42,610	(99,596)	5,820,950
Beginning Balance at Dec. 31, 2019		2,500	5,142,936	(46,693)	428,612	5,527,355
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital			(207,000)			(207,000)
Comprehensive income:
Net income (loss)	(820,788)			(820,788)		(820,788)
Other comprehensive income (loss), net of tax	$ 1,010,888				1,010,888	1,010,888
Total comprehensive income (loss)						190,100
Ending Balance at Mar. 31, 2020		$ 2,500	$ 4,935,936	$ (868,873)	$ 1,439,500	$ 5,509,063