Securities - Amortized Cost and Estimated Fair Value of Securities Available-for-Sale and Held-to-Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	$ 569,874	$ 180,154
Available-for-sale, gross unrealized gains	1,275	3,154
Available-for-sale, gross unrealized losses	(2,894)	(6)
Available-for-sale, fair value	568,255	183,302
Allowance for securities credit losses	0	0
Amortized Cost	1,143,548	942,314
Held-to-maturity, gross unrealized losses	18,967	29,378
Held-to-maturity, gross unrealized losses	(9,771)	(3,226)
Debt securities held-to-maturity	1,152,744	968,466
Allowance for securities credit losses	(1,467)	(1,715)	$ 0
Total, amortized cost	1,713,422	1,122,468
Total, gross unrealized gains	20,242	32,532
Total, gross unrealized losses	(12,665)	(3,232)
Total, estimated fair value	1,720,999	1,151,768
U.S. government and agency obligations \| Investment securities
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	164,756	173,790
Available-for-sale, gross unrealized gains	1,135	3,152
Available-for-sale, gross unrealized losses	(471)	(2)
Available-for-sale, fair value	165,420	176,940
Allowance for securities credit losses	0	0
Corporate debt securities
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	66,200
Available-for-sale, fair value	66,400
Corporate debt securities \| Investment securities
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	5,000
Available-for-sale, gross unrealized gains	42
Available-for-sale, gross unrealized losses	(11)
Available-for-sale, fair value	5,031
Allowance for securities credit losses	0
Amortized Cost	68,823	72,305
Held-to-maturity, gross unrealized losses	1,628	1,615
Held-to-maturity, gross unrealized losses	(1,279)	(2,652)
Debt securities held-to-maturity	69,172	71,268
Allowance for securities credit losses	(1,343)	(1,550)
Asset-backed securities \| Investment securities
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	298,976	6,174
Available-for-sale, gross unrealized gains	41	0
Available-for-sale, gross unrealized losses	(1,489)	(4)
Available-for-sale, fair value	297,528	6,170
Allowance for securities credit losses	0	0
State, municipal, and sovereign debt obligations
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	90,200
Available-for-sale, fair value	92,500
State, municipal, and sovereign debt obligations \| Investment securities
Securities Financing Transaction [Line Items]
Amortized Cost	281,389	238,405
Held-to-maturity, gross unrealized losses	10,185	11,500
Held-to-maturity, gross unrealized losses	(1,164)	(231)
Debt securities held-to-maturity	290,410	249,674
Allowance for securities credit losses	(85)	(48)
Mortgage-backed securities:
Securities Financing Transaction [Line Items]
Amortized Cost	793,336	631,604
Held-to-maturity, gross unrealized losses	7,154	16,263
Held-to-maturity, gross unrealized losses	(7,328)	(343)
Debt securities held-to-maturity	793,162	647,524
Allowance for securities credit losses	(39)	(117)
Mortgage-backed securities: \| Agency residential
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost		190
Available-for-sale, gross unrealized gains		2
Available-for-sale, gross unrealized losses		0
Available-for-sale, fair value		192
Allowance for securities credit losses		0
Amortized Cost	756,844	593,891
Held-to-maturity, gross unrealized losses	6,785	15,037
Held-to-maturity, gross unrealized losses	(7,180)	(283)
Debt securities held-to-maturity	756,449	608,645
Allowance for securities credit losses	0	0
Mortgage-backed securities: \| Agency commercial
Securities Financing Transaction [Line Items]
Available-for-sale, amortized cost	101,142
Available-for-sale, gross unrealized gains	57
Available-for-sale, gross unrealized losses	(923)
Available-for-sale, fair value	100,276
Allowance for securities credit losses	0
Amortized Cost	4,385	5,392
Held-to-maturity, gross unrealized losses	7	0
Held-to-maturity, gross unrealized losses	(44)	(60)
Debt securities held-to-maturity	4,348	5,332
Allowance for securities credit losses	0	0
Mortgage-backed securities: \| Non-agency commercial
Securities Financing Transaction [Line Items]
Amortized Cost	32,107	32,321
Held-to-maturity, gross unrealized losses	362	1,226
Held-to-maturity, gross unrealized losses	(104)	0
Debt securities held-to-maturity	32,365	33,547
Allowance for securities credit losses	$ (39)	$ (117)

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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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