Securities - Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	$ 5,898,041	$ 4,997,529
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	70,839	219,873
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(57,881)	(7,268)
Debt Securities, Available-for-sale	5,910,999	5,210,134
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Total	2,148,327	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	50
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(25,771)
Debt Securities, Held-to-maturity, Fair Value	2,122,606	0
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	3,738,616	3,640,351
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	45,077	178,579
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(38,092)	(4,543)
Debt Securities, Available-for-sale	3,745,601	3,814,387
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Total	2,148,327
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	50
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(25,771)
Debt Securities, Held-to-maturity, Fair Value	2,122,606
Asset-backed Securities
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	469,052	349,904
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,802	9,651
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(9,791)	(2,076)
Debt Securities, Available-for-sale	463,063	357,479
State and Municipal Securities
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	983,704	729,066
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	18,525	25,098
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(4,938)	(592)
Debt Securities, Available-for-sale	997,291	753,572
US Government Corporations and Agencies Securities [Member]
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	252,755	278,208
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,095	6,545
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(3,274)	(57)
Debt Securities, Available-for-sale	252,576	$ 284,696
US Government Securities
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	158,367
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(831)
Debt Securities, Available-for-sale	157,536
Non-agency collateralized mortgage obligations
Debt Securities [Line Items]
Debt Securities Available-for-Sale, Amortized Cost	295,547
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	340
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(955)
Debt Securities, Available-for-sale	$ 294,932

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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