Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ 124,871	$ 84,502	$ (1,674,150)	$ 270,345
Available for sale securities:
Unrealized gains arising during the period	2,996	26,352	115,327	100,381
Income tax expense related to unrealized gains	(771)	(6,778)	(29,663)	(25,819)
Reclassification adjustment for net realized (gains) losses in earnings	0	0	(190)	7,186
Income tax expense (benefit) related to realized losses	0	0	49	(1,848)
Net change in unrealized gains for available for sale securities	2,225	19,574	85,523	79,900
Junior subordinated debentures, at fair value:
Unrealized (losses) gains arising during the period	(14,555)	8,450	26,857	32,254
Income tax benefit (expense) related to unrealized gains	3,744	(2,173)	(6,907)	(8,276)
Net change in unrealized (losses) gains for junior subordinated debentures, at fair value	(10,811)	6,277	19,950	23,978
Other comprehensive (loss) income, net of tax	(8,586)	25,851	105,473	103,878
Comprehensive income (loss)	$ 116,285	$ 110,353	$ (1,568,677)	$ 374,223