Investment Securities, AFS and HTM Securities Amortized Costs and Fair Values (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	$ 2,997,032	$ 4,338,671
Debt Securities, Available-for-sale, Unrealized Gain	830	28,850
Debt Securities, Available-for-sale, Unrealized Loss	(255,837)	(35,506)
Debt Securities, Available-for-sale	2,742,025	4,332,015
HTM investment securities
Investment securities held to maturity	3,960,451	2,239,003
Gross Unrealized Gains	60,978	118,471
Held-to-maturity, Gross Unrealized Loss	(620,411)	(8,809)
Fair Value	3,401,018	2,348,664
US Treasury Securities [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	124,441	124,291
Debt Securities, Available-for-sale, Unrealized Gain	0	0
Debt Securities, Available-for-sale, Unrealized Loss	(15,063)	(1,334)
Debt Securities, Available-for-sale	109,378	122,957
HTM investment securities
Investment securities held to maturity	999	1,000
Gross Unrealized Gains	0	1
Held-to-maturity, Gross Unrealized Loss	(62)	0
Fair Value	936	1,001
US States and Political Subdivisions Debt Securities [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	235,693	381,517
Debt Securities, Available-for-sale, Unrealized Gain	96	18,940
Debt Securities, Available-for-sale, Unrealized Loss	(5,074)	0
Debt Securities, Available-for-sale	230,714	400,457
HTM investment securities
Investment securities held to maturity	1,732,351	1,628,759
Gross Unrealized Gains	1,994	113,179
Held-to-maturity, Gross Unrealized Loss	(182,697)	(1,951)
Fair Value	1,551,647	1,739,988
Residential Related Securities \| FNMA/FHLMC [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	1,820,642	2,709,399
Debt Securities, Available-for-sale, Unrealized Gain	404	3,729
Debt Securities, Available-for-sale, Unrealized Loss	(216,436)	(21,249)
Debt Securities, Available-for-sale	1,604,610	2,691,879
HTM investment securities
Investment securities held to maturity	961,231	34,347
Gross Unrealized Gains	31,301	1,792
Held-to-maturity, Gross Unrealized Loss	(175,760)	0
Fair Value	816,771	36,139
Residential Related Securities \| Government National Mortgage Association (GNMA)
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	502,537	66,189
Debt Securities, Available-for-sale, Unrealized Gain	314	1,591
Debt Securities, Available-for-sale, Unrealized Loss	(5,255)	0
Debt Securities, Available-for-sale	497,596	67,780
HTM investment securities
Investment securities held to maturity	52,979	48,053
Gross Unrealized Gains	85	1,578
Held-to-maturity, Gross Unrealized Loss	(3,436)	0
Fair Value	49,628	49,631
Mortgage-Backed Securities, Issued by Private Enterprises [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	0	332,028
Debt Securities, Available-for-sale, Unrealized Gain		31
Debt Securities, Available-for-sale, Unrealized Loss		2,335
Debt Securities, Available-for-sale	0	329,724
HTM investment securities
Investment securities held to maturity	364,728
Gross Unrealized Gains	11,697
Held-to-maturity, Gross Unrealized Loss	(72,920)
Fair Value	303,505
Commercial Mortgage-Backed Securities [Member] \| FNMA/FHLMC [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	19,038	357,240
Debt Securities, Available-for-sale, Unrealized Gain	0	2,686
Debt Securities, Available-for-sale, Unrealized Loss	(1,896)	(9,302)
Debt Securities, Available-for-sale	17,142	350,623
HTM investment securities
Investment securities held to maturity	778,796	425,937
Gross Unrealized Gains	15,324	122
Held-to-maturity, Gross Unrealized Loss	(178,281)	(6,659)
Fair Value	615,839	419,400
Commercial Mortgage-Backed Securities [Member] \| Government National Mortgage Association (GNMA)
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	115,031	165,439
Debt Securities, Available-for-sale, Unrealized Gain	0	1,360
Debt Securities, Available-for-sale, Unrealized Loss	(4,569)	0
Debt Securities, Available-for-sale	110,462	166,799
HTM investment securities
Investment securities held to maturity	69,369	100,907
Gross Unrealized Gains	577	1,799
Held-to-maturity, Gross Unrealized Loss	(7,254)	(200)
Fair Value	62,691	102,506
FFELP asset backed securities
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	157,138	177,974
Debt Securities, Available-for-sale, Unrealized Gain	0	475
Debt Securities, Available-for-sale, Unrealized Loss	(5,947)	(1,123)
Debt Securities, Available-for-sale	151,191	177,325
HTM investment securities
Investment securities held to maturity	0
Fair Value	0
Debt Securities [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	3,000	3,000
Debt Securities, Available-for-sale, Unrealized Gain	0	0
Debt Securities, Available-for-sale, Unrealized Loss	(78)	(6)
Debt Securities, Available-for-sale	2,922	2,994
Agency Securities [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	15,000	15,000
Debt Securities, Available-for-sale, Unrealized Gain	0	0
Debt Securities, Available-for-sale, Unrealized Loss	(1,468)	(103)
Debt Securities, Available-for-sale	13,532	14,897
US Government-sponsored Enterprises Debt Securities [Member]
AFS investment securities
Debt Securities, Available-for-sale, Amortized Cost	4,512	6,594
Debt Securities, Available-for-sale, Unrealized Gain	15	39
Debt Securities, Available-for-sale, Unrealized Loss	(51)	(54)
Debt Securities, Available-for-sale	4,477	$ 6,580
HTM investment securities
Investment securities held to maturity	0
Fair Value	$ 0

Amortized cost of 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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