CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Comprehensive income (loss):
Net income (loss)	$ 118,108	$ 115,017	$ 357,116	$ 277,824
Other comprehensive income:
Unrealized gains (losses) on available-for-sale securities, net	(42,341)	41,655	(131,157)	37,744
Reclassification adjustment for net losses included in net income for other-than-temporary credit impairment losses	9,131	13,509	10,289	32,210
Reclassification adjustment for net realized losses (gains) included in net income	(4,383)	(2,591)	(4,383)	(7,777)
Other comprehensive income (loss)	(37,593)	52,573	(125,251)	62,177
Comprehensive income (loss) before preferred stock dividends	80,515	167,590	231,865	340,001
Dividends on preferred stock	9,400	9,400	18,800	14,683
Comprehensive income (loss) available to common stock shareholders	$ 71,115	$ 158,190	$ 213,065	$ 325,318