Securities (Schedule of Debt Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
AFS debt securities:
Amortized Cost	$ 7,091,581	$ 10,087,179
Gross Unrealized Gains	6,246	51,025
Gross Unrealized Losses	(368,396)	(172,851)
Fair Value	6,729,431	9,965,353
HTM debt securities:
Amortized Cost	2,997,702	0
Gross Unrealized Gains	0
Gross Unrealized Losses	(181,734)
Fair Value	2,815,968
Total debt securities
Amortized Cost	10,089,283
Gross Unrealized Gains	6,246
Gross Unrealized Losses	(550,130)
Fair Value	9,545,399
U.S. Treasury securities
AFS debt securities:
Amortized Cost	676,330	1,049,238
Gross Unrealized Gains	64	130
Gross Unrealized Losses	(38,420)	(16,687)
Fair Value	637,974	1,032,681
HTM debt securities:
Amortized Cost	519,989
Gross Unrealized Gains	0
Gross Unrealized Losses	(20,714)
Fair Value	499,275
U.S. government agency and U.S. government-sponsored enterprise debt securities
AFS debt securities:
Amortized Cost	326,555	1,333,984
Gross Unrealized Gains	119	2,697
Gross Unrealized Losses	(22,279)	(34,710)
Fair Value	304,395	1,301,971
HTM debt securities:
Amortized Cost	946,763
Gross Unrealized Gains	0
Gross Unrealized Losses	(67,477)
Fair Value	879,286
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	632,660	1,242,043
Gross Unrealized Gains	1,185	15,791
Gross Unrealized Losses	(33,522)	(28,854)
Fair Value	600,323	1,228,980
HTM debt securities:
Amortized Cost	515,966
Gross Unrealized Gains	0
Gross Unrealized Losses	(31,678)
Fair Value	484,288
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
AFS debt securities:
Amortized Cost	2,180,621	2,968,789
Gross Unrealized Gains	733	8,629
Gross Unrealized Losses	(112,869)	(49,135)
Fair Value	2,068,485	2,928,283
HTM debt securities:
Amortized Cost	824,713
Gross Unrealized Gains	0
Gross Unrealized Losses	(44,690)
Fair Value	780,023
Municipal securities
AFS debt securities:
Amortized Cost	317,952	519,381
Gross Unrealized Gains	749	10,065
Gross Unrealized Losses	(20,042)	(6,288)
Fair Value	298,659	523,158
HTM debt securities:
Amortized Cost	190,271
Gross Unrealized Gains	0
Gross Unrealized Losses	(17,175)
Fair Value	173,096
Non-agency commercial mortgage-backed securities
AFS debt securities:
Amortized Cost	468,203	498,920
Gross Unrealized Gains	647	3,000
Gross Unrealized Losses	(23,525)	(5,477)
Fair Value	445,325	496,443
Non-agency residential mortgage-backed securities
AFS debt securities:
Amortized Cost	855,502	889,937
Gross Unrealized Gains	7	971
Gross Unrealized Losses	(48,727)	(8,977)
Fair Value	806,782	881,931
Corporate debt securities
AFS debt securities:
Amortized Cost	683,502	657,516
Gross Unrealized Gains	2,107	8,738
Gross Unrealized Losses	(55,097)	(16,589)
Fair Value	630,512	649,665
Foreign government bonds
AFS debt securities:
Amortized Cost	260,846	260,447
Gross Unrealized Gains	635	767
Gross Unrealized Losses	(7,670)	(3,481)
Fair Value	253,811	257,733
Asset-backed securities
AFS debt securities:
Amortized Cost	72,160	74,674
Gross Unrealized Gains	0	185
Gross Unrealized Losses	(798)	(301)
Fair Value	71,362	74,558
Collateralized loan obligations (“CLOs”)
AFS debt securities:
Amortized Cost	617,250	592,250
Gross Unrealized Gains	0	52
Gross Unrealized Losses	(5,447)	(2,352)
Fair Value	$ 611,803	$ 589,950