Securities (Schedule of Available-for-sale Debt Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Debt Securities
Amortized Cost	$ 8,411,142	$ 5,470,523
Gross Unrealized Gains	77,109	96,596
Gross Unrealized Losses	(88,791)	(22,461)
Fair Value	8,399,460	5,544,658
U.S. Treasury securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	841,890	50,310
Gross Unrealized Gains	1,148	451
Gross Unrealized Losses	(6,098)	0
Fair Value	836,940	50,761
U.S. government agency and U.S. government-sponsored enterprise debt securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	1,237,278	806,814
Gross Unrealized Gains	5,835	8,765
Gross Unrealized Losses	(18,602)	(1,260)
Fair Value	1,224,511	814,319
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	1,177,949	1,125,174
Gross Unrealized Gains	23,374	34,306
Gross Unrealized Losses	(12,683)	(5,710)
Fair Value	1,188,640	1,153,770
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	2,375,536	1,634,553
Gross Unrealized Gains	18,186	27,952
Gross Unrealized Losses	(25,170)	(1,611)
Fair Value	2,368,552	1,660,894
Municipal securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	445,028	382,573
Gross Unrealized Gains	11,532	13,588
Gross Unrealized Losses	(1,637)	(88)
Fair Value	454,923	396,073
Non-agency commercial mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	360,704	234,965
Gross Unrealized Gains	5,282	6,107
Gross Unrealized Losses	(1,814)	(1,230)
Fair Value	364,172	239,842
Non-agency residential mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	772,382	288,520
Gross Unrealized Gains	2,308	1,761
Gross Unrealized Losses	(2,216)	(506)
Fair Value	772,474	289,775
Corporate debt securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	558,295	406,323
Gross Unrealized Gains	8,597	3,493
Gross Unrealized Losses	(14,177)	(3,848)
Fair Value	552,715	405,968
Foreign government bonds
Schedule of Available-for-sale Debt Securities
Amortized Cost	286,579	183,828
Gross Unrealized Gains	512	163
Gross Unrealized Losses	(3,916)	(1,460)
Fair Value	283,175	182,531
Asset-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	61,501	63,463
Gross Unrealized Gains	335	10
Gross Unrealized Losses	(7)	(242)
Fair Value	61,829	63,231
Collateralized loan obligations (“CLOs”)
Schedule of Available-for-sale Debt Securities
Amortized Cost	294,000	294,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,471)	(6,506)
Fair Value	$ 291,529	$ 287,494

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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