Securities - Summary of Amortized Cost and Fair Values of Securities Available-for-sale (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	$ 1,688,715	$ 1,418,445
Available-for-sale Securities, Gross Unrealized Gains	15,463	29,834
Available-for-sale Securities, Gross Unrealized Losses	(28,271)	(1,049)
Available-for-sale Securities, Fair Value	1,675,907	1,447,230
U.S. Treasury Notes
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	13,475	23,468
Available-for-sale Securities, Gross Unrealized Gains	243	344
Available-for-sale Securities, Fair Value	13,718	23,812
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	142,134	113,088
Available-for-sale Securities, Gross Unrealized Gains	721	600
Available-for-sale Securities, Gross Unrealized Losses	(3,270)	(137)
Available-for-sale Securities, Fair Value	139,585	113,551
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	102,966	135,513
Available-for-sale Securities, Gross Unrealized Gains	3,854	6,991
Available-for-sale Securities, Gross Unrealized Losses	(292)	(85)
Available-for-sale Securities, Fair Value	106,528	142,419
Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	985,375	764,951
Available-for-sale Securities, Gross Unrealized Gains	4,802	13,645
Available-for-sale Securities, Gross Unrealized Losses	(19,085)	(205)
Available-for-sale Securities, Fair Value	971,092	778,391
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	68,562	32,654
Available-for-sale Securities, Gross Unrealized Gains	149	332
Available-for-sale Securities, Gross Unrealized Losses	(761)	(5)
Available-for-sale Securities, Fair Value	67,950	32,981
Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	269,997	244,496
Available-for-sale Securities, Gross Unrealized Gains	4,009	6,046
Available-for-sale Securities, Gross Unrealized Losses	(4,795)	(390)
Available-for-sale Securities, Fair Value	269,211	250,152
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	61,018	59,020
Available-for-sale Securities, Gross Unrealized Gains	1,602	1,850
Available-for-sale Securities, Gross Unrealized Losses	(68)	(102)
Available-for-sale Securities, Fair Value	62,552	60,768
Asset-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	45,188	45,255
Available-for-sale Securities, Gross Unrealized Gains	83	26
Available-for-sale Securities, Gross Unrealized Losses		(125)
Available-for-sale Securities, Fair Value	$ 45,271	$ 45,156

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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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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