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Securities (Debt securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	$ 5,647,523	$ 5,898,041
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,703	70,839
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(526,658)	(57,881)
Debt securities available for sale at fair value	5,122,568	5,910,999
Debt Securities, Held-to-Maturity, Amortized Cost	2,149,255	2,148,327
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	50
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	236,729	25,771
Debt Securities, Held-to-maturity, Fair Value	1,912,526	2,122,606
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	3,447,262	3,738,616
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,016	45,077
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(309,514)	(38,092)
Debt securities available for sale at fair value	3,138,764	3,745,601
Debt Securities, Held-to-Maturity, Amortized Cost	2,149,255	2,148,327
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	50
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	236,729	25,771
Debt Securities, Held-to-maturity, Fair Value	1,912,526	2,122,606
Asset-backed Securities [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	419,448	469,052
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	3,802
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(39,480)	(9,791)
Debt securities available for sale at fair value	379,968	463,063
State and Municipal Securities [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	989,070	983,704
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	629	18,525
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(111,371)	(4,938)
Debt securities available for sale at fair value	878,328	997,291
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	240,375	252,755
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	58	3,095
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(11,005)	(3,274)
Debt securities available for sale at fair value	229,428	252,576
US Treasury Securities [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	182,681	158,367
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(11,362)	(831)
Debt securities available for sale at fair value	171,319	157,536
Non-agency collateralized mortgage obligations [Member]
Debt Securities, [Line Items]
Debt securities available-for-sale, amortized cost	368,687	295,547
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	340
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(43,926)	(955)
Debt securities available for sale at fair value	$ 324,761	$ 294,932

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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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