Investment Securities - Summary of Amortized Cost and Fair Value of Securities (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Abstract]
Amortized cost	$ 1,740,785,000	$ 1,673,798,000
Gross unrealized gains	100,000	23,120,000
Gross unrealized losses	(258,714,000)	(18,393,000)
Allowance for credit losses for investments	0	0
Fair Value	1,482,171,000	1,678,525,000
U.S. government agency securities
Debt Securities, Available-for-sale [Abstract]
Amortized cost	45,161,000	34,023,000
Gross unrealized gains	0	18,000
Gross unrealized losses	(5,330,000)	(171,000)
Allowance for credit losses for investments	0	0
Fair Value	39,831,000	33,870,000
Mortgage-backed securities - residential
Debt Securities, Available-for-sale [Abstract]
Amortized cost	1,257,521,000	1,281,285,000
Gross unrealized gains	0	6,072,000
Gross unrealized losses	(199,758,000)	(17,985,000)
Allowance for credit losses for investments	0	0
Fair Value	1,057,763,000	1,269,372,000
Mortgage-backed securities - commercial
Debt Securities, Available-for-sale [Abstract]
Amortized cost	19,453,000	15,024,000
Gross unrealized gains	0	272,000
Gross unrealized losses	(1,606,000)	(46,000)
Allowance for credit losses for investments	0	0
Fair Value	17,847,000	15,250,000
Municipal securities
Debt Securities, Available-for-sale [Abstract]
Amortized cost	297,451,000	322,052,000
Gross unrealized gains	100,000	16,718,000
Gross unrealized losses	(45,408,000)	(160,000)
Allowance for credit losses for investments	0	0
Fair Value	252,143,000	338,610,000
U.S. Treasury securities
Debt Securities, Available-for-sale [Abstract]
Amortized cost	113,198,000	14,914,000
Gross unrealized gains	0	0
Gross unrealized losses	(5,901,000)	(6,000)
Allowance for credit losses for investments	0	0
Fair Value	107,297,000	14,908,000
Corporate securities
Debt Securities, Available-for-sale [Abstract]
Amortized cost	8,001,000	6,500,000
Gross unrealized gains	0	40,000
Gross unrealized losses	(711,000)	(25,000)
Allowance for credit losses for investments	0	0
Fair Value	$ 7,290,000	$ 6,515,000

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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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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Amount excluding accrued interest, of allowance for credit loss 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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-Publisher FASB
-Name Accounting Standards Codification
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