Securities - Amortized Cost and Fair Value of Securities Available for Sale and Held for Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	$ 2,239,127	$ 2,119,303
Available for sale, gross unrealized gains	1,595	1,101
Available for sale, gross unrealized losses	(224,755)	(248,662)
Available for sale, fair value	2,015,967	1,871,742
Held-to-Maturity Debt Securities
Held to maturity, amortized cost, total	737,911	747,408
Held to maturity, gross unrealized gains	0	64
Held to maturity, gross unrealized losses	(119,135)	(129,731)
Held to maturity, fair value	618,776	617,741
U.S. Treasury securities and obligations of U.S. government agencies
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	43,448	13,813
Available for sale, gross unrealized gains	267	173
Available for sale, gross unrealized losses	(331)	(339)
Available for sale, fair value	43,384	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	1,657,149	1,561,197
Available for sale, gross unrealized gains	1,002	539
Available for sale, gross unrealized losses	(203,663)	(223,083)
Available for sale, fair value	1,454,488	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	175,629	179,148
Available for sale, gross unrealized gains	104	70
Available for sale, gross unrealized losses	(12,359)	(12,831)
Available for sale, fair value	163,374	166,387
Collateralized loan obligations
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	312,086	313,155
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(6,609)	(10,251)
Available for sale, fair value	305,477	302,904
Obligations of state and political subdivisions
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	22,016	29,350
Available for sale, gross unrealized gains	38	122
Available for sale, gross unrealized losses	(1,383)	(1,731)
Available for sale, fair value	20,671	27,741
Other debt securities
Available-for-Sale Debt Securities
Available for sale, amortized cost, total	28,799	22,640
Available for sale, gross unrealized gains	184	197
Available for sale, gross unrealized losses	(410)	(427)
Available for sale, fair value	28,573	$ 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	737,911
Held to maturity, gross unrealized gains	0
Held to maturity, gross unrealized losses	(119,135)
Held to maturity, fair value	$ 618,776

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

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