Allowance for Credit Losses (“ACL”) on Loans - Amount of Loans Receivable Held-for-Investment and Related Allowances Per Loan Portfolio Segment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 41,154,000	$ 39,031,000	$ 42,617,000	$ 38,973,000
Charge-offs	(2,904,000)	(75,000)	(5,323,000)	(785,000)
Recoveries	42,000	224,000	104,000	440,000
Provisions (credit)	188,000	2,703,000	1,082,000	3,255,000
Ending balance	38,480,000	41,883,000	38,480,000	41,883,000
Originated Loans Net
Ending balance: individually evaluated for impairment	45,300		45,300		$ 38,200
Ending balance: collectively evaluated for impairment	35,327,000		35,327,000		38,696,000
Ending balance: PCD loans evaluated for impairment	3,108,000		3,108,000		3,883,000
Ending balance	4,229,974,000		4,229,974,000		4,243,693,000
Ending balance: individually evaluated for impairment	8,416,000		8,416,000		8,939,000
Ending balance: collectively evaluated for impairment	4,210,862,000		4,210,862,000		4,218,109,000
Ending balance: PCD loans evaluated for impairment	10,371,000		10,371,000		11,502,000
PPP loans not evaluated for impairment	325,000		325,000		5,143,000
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	37,428,000	34,873,000	38,734,000	34,241,000
Charge-offs	(2,904,000)	0	(5,315,000)	(185,000)
Recoveries	34,000	46,000	96,000	262,000
Provisions (credit)	814,000	2,942,000	1,857,000	3,543,000
Ending balance	35,372,000	37,861,000	35,372,000	37,861,000
Originated Loans Net
Ending balance: individually evaluated for impairment	45,000		45,000		38,000
Ending balance: collectively evaluated for impairment	35,327,000		35,327,000		38,696,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	4,219,603,000		4,219,603,000		4,232,191,000
Ending balance: individually evaluated for impairment	8,416,000		8,416,000		8,939,000
Ending balance: collectively evaluated for impairment	4,210,862,000		4,210,862,000		4,218,109,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	325,000		325,000		5,143,000
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real Estate
Originated Loans Net
Ending balance	4,072,741,000		4,072,741,000		4,075,261,000
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial and industrial loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	7,295,000	2,705,000	4,114,000	3,173,000
Charge-offs	(2,904,000)	0	(5,315,000)	(185,000)
Recoveries	20,000	12,000	47,000	131,000
Provisions (credit)	1,391,000	238,000	6,956,000	(164,000)
Ending balance	5,802,000	2,955,000	5,802,000	2,955,000
Originated Loans Net
Ending balance: individually evaluated for impairment	18,000		18,000		18,000
Ending balance: collectively evaluated for impairment	5,784,000		5,784,000		4,096,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	144,788,000		144,788,000		154,700,000
Ending balance: individually evaluated for impairment	87,000		87,000		94,000
Ending balance: collectively evaluated for impairment	144,376,000		144,376,000		149,463,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	325,000		325,000		5,143,000
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Other loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	7,000	11,000	9,000	9,000
Charge-offs	0	0	0	0
Recoveries	0	4,000	0	4,000
Provisions (credit)	0	(9,000)	(2,000)	(7,000)
Ending balance	7,000	6,000	7,000	6,000
Originated Loans Net
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	7,000		7,000		9,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	2,074,000		2,074,000		2,230,000
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	2,074,000		2,074,000		2,230,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	0		0		0
PCD loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,726,000	4,158,000	3,883,000	4,732,000
Charge-offs	0	(75,000)	(8,000)	(600,000)
Recoveries	8,000	178,000	8,000	178,000
Provisions (credit)	(626,000)	(239,000)	(775,000)	(288,000)
Ending balance	3,108,000	4,022,000	3,108,000	4,022,000
Originated Loans Net
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	0		0		0
Ending balance: PCD loans evaluated for impairment	3,108,000		3,108,000		3,883,000
Ending balance	10,371,000		10,371,000		11,502,000
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	0		0		0
Ending balance: PCD loans evaluated for impairment	10,371,000		10,371,000		11,502,000
PPP loans not evaluated for impairment	0		0		0
Commercial | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24,733,000	28,065,000	29,485,000	26,785,000
Charge-offs	0	0	0	0
Recoveries	14,000	4,000	48,000	101,000
Provisions (credit)	(409,000)	2,117,000	(5,195,000)	3,300,000
Ending balance	24,338,000	30,186,000	24,338,000	30,186,000
Originated Loans Net
Ending balance: individually evaluated for impairment	24,000		24,000		18,000
Ending balance: collectively evaluated for impairment	24,313,000		24,313,000		29,467,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	3,715,128,000		3,715,128,000		3,723,828,000
Ending balance: individually evaluated for impairment	7,681,000		7,681,000		8,152,000
Ending balance: collectively evaluated for impairment	3,707,447,000		3,707,447,000		3,715,676,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	0		0		0
One-to-four family residential mortgage | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,814,000	3,005,000	3,936,000	3,545,000
Charge-offs	0	0	0	0
Recoveries	0	7,000	0	7,000
Provisions (credit)	(243,000)	553,000	(365,000)	13,000
Ending balance	3,571,000	3,565,000	3,571,000	3,565,000
Originated Loans Net
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	3,571,000		3,571,000		3,936,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	164,525,000		164,525,000		173,946,000
Ending balance: individually evaluated for impairment	624,000		624,000		666,000
Ending balance: collectively evaluated for impairment	163,901,000		163,901,000		173,280,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	0		0		0
Home equity and lines of credit | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,278,000	802,000	866,000	560,000
Charge-offs	0	0	0	0
Recoveries	0	19,000	1,000	19,000
Provisions (credit)	77,000	53,000	488,000	295,000
Ending balance	1,355,000	874,000	1,355,000	874,000
Originated Loans Net
Ending balance: individually evaluated for impairment	3,000		3,000		2,000
Ending balance: collectively evaluated for impairment	1,353,000		1,353,000		864,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	160,798,000		160,798,000		152,555,000
Ending balance: individually evaluated for impairment	24,000		24,000		27,000
Ending balance: collectively evaluated for impairment	160,774,000		160,774,000		152,528,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	0		0		0
Construction and land | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	301,000	285,000	324,000	169,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provisions (credit)	(2,000)	(10,000)	(25,000)	106,000
Ending balance	299,000	$ 275,000	299,000	$ 275,000
Originated Loans Net
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	299,000		299,000		324,000
Ending balance: PCD loans evaluated for impairment	0		0		0
Ending balance	32,290,000		32,290,000		24,932,000
Ending balance: individually evaluated for impairment	0		0		0
Ending balance: collectively evaluated for impairment	32,290,000		32,290,000		24,932,000
Ending balance: PCD loans evaluated for impairment	0		0		0
PPP loans not evaluated for impairment	$ 0		$ 0		$ 0