CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Comprehensive income (loss):
Net income (loss)	$ 411,637	$ 524,668	$ 551,943
Other comprehensive income:
Unrealized gains (losses) on available-for-sale securities, net	(185,570)	24,218	(88,527)
Reclassification adjustment for net losses included in net income for other-than-temporary credit impairment losses	21,791	61,856	57,987
Reclassification adjustment for net realized losses (gains) included in net income	(6,291)	(7,278)	(25,145)
Other comprehensive income (loss)	(170,070)	78,796	(55,685)
Comprehensive income (loss) before preferred stock dividends	241,567	603,464	496,258
Dividends on preferred stock	43,197	33,484	2,449
Comprehensive income (loss) available to common stock shareholders	$ 198,370	$ 569,980	$ 493,809