Securities - Amortized Cost and Fair Value of Securities Available for Sale and Held for Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	$ 2,168,686	$ 2,119,303
Available for sale, gross unrealized gains	921	1,101
Available for sale, gross unrealized losses	(253,376)	(248,662)
Available for sale, fair value	1,916,231	1,871,742
Held-to-Maturity Debt Securities
Held to maturity, amortized cost, total	707,812	747,408
Held to maturity, gross unrealized gains	0	64
Held to maturity, gross unrealized losses	(130,226)	(129,731)
Held to maturity, fair value	577,586	617,741
U.S. Treasury securities and obligations of U.S. government agencies
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	41,283	13,813
Available for sale, gross unrealized gains	188	173
Available for sale, gross unrealized losses	(497)	(339)
Available for sale, fair value	40,974	13,647
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	1,623,932	1,561,197
Available for sale, gross unrealized gains	301	539
Available for sale, gross unrealized losses	(230,690)	(223,083)
Available for sale, fair value	1,393,543	1,338,653
Held-to-Maturity Debt Securities
Held to maturity, amortized cost, total		747,408
Held to maturity, gross unrealized gains		64
Held to maturity, gross unrealized losses		(129,731)
Held to maturity, fair value		617,741
Private mortgage-backed securities and collateralized mortgage obligations
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	143,008	179,148
Available for sale, gross unrealized gains	15	70
Available for sale, gross unrealized losses	(13,352)	(12,831)
Available for sale, fair value	129,671	166,387
Collateralized loan obligations
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	310,516	313,155
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(7,204)	(10,251)
Available for sale, fair value	303,312	302,904
Obligations of state and political subdivisions
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	21,956	29,350
Available for sale, gross unrealized gains	2	122
Available for sale, gross unrealized losses	(1,506)	(1,731)
Available for sale, fair value	20,452	27,741
Other debt securities
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	27,991	22,640
Available for sale, gross unrealized gains	415	197
Available for sale, gross unrealized losses	(127)	(427)
Available for sale, fair value	28,279	$ 22,410
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Held-to-Maturity Debt Securities
Held to maturity, amortized cost, total	707,812
Held to maturity, gross unrealized gains	0
Held to maturity, gross unrealized losses	(130,226)
Held to maturity, fair value	$ 577,586

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 excluding accrued interest, after allowance for credit loss, 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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Amount excluding accrued interest, 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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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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