Securities (Schedule of Available-for-sale Debt Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Debt Securities
Amortized Cost	$ 3,660,413	$ 3,320,648
Gross Unrealized Gains	84,357	19,805
Gross Unrealized Losses	(48,827)	(23,239)
AFS debt securities	3,695,943	3,317,214
U.S. Treasury securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	50,606	177,215
Gross Unrealized Gains	822	0
Gross Unrealized Losses	0	(793)
AFS debt securities	51,428	176,422
U.S. government agency and U.S. government-sponsored enterprise debt securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	511,176	584,275
Gross Unrealized Gains	7,232	1,377
Gross Unrealized Losses	0	(4,407)
AFS debt securities	518,408	581,245
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	677,644	599,814
Gross Unrealized Gains	24,472	8,551
Gross Unrealized Losses	(4,168)	(4,894)
AFS debt securities	697,948	603,471
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	1,316,009	998,447
Gross Unrealized Gains	38,770	6,927
Gross Unrealized Losses	(2,412)	(1,477)
AFS debt securities	1,352,367	1,003,897
Municipal securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	300,551	101,621
Gross Unrealized Gains	10,147	790
Gross Unrealized Losses	(1,072)	(109)
AFS debt securities	309,626	102,302
Non-agency commercial mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	85,843	86,609
Gross Unrealized Gains	2,008	1,947
Gross Unrealized Losses	(737)	(6)
AFS debt securities	87,114	88,550
Non-agency residential mortgage-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	64,112	46,830
Gross Unrealized Gains	156	3
Gross Unrealized Losses	(2,134)	(285)
AFS debt securities	62,134	46,548
Corporate debt securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	11,250	11,250
Gross Unrealized Gains	1	12
Gross Unrealized Losses	(288)	(113)
AFS debt securities	10,963	11,149
Foreign bonds
Schedule of Available-for-sale Debt Securities
Amortized Cost	283,822	354,481
Gross Unrealized Gains	749	198
Gross Unrealized Losses	(50)	(507)
AFS debt securities	284,521	354,172
Asset-backed securities
Schedule of Available-for-sale Debt Securities
Amortized Cost	65,400	66,106
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3,844)	(1,354)
AFS debt securities	61,556	64,752
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	(34,122)	(9,294)
AFS debt securities	$ 259,878	$ 284,706