Loans - Loans Held-for-Investment and Current Period Gross Charge-Offs, Excluding PCD Loans, Net of Deferred Fees and Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Ending balance	$ 4,229,974		$ 4,229,974		$ 4,243,693
Current period gross charge-offs
Total	2,904	$ 75	5,323	$ 785
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	205,399		205,399		939,431
Year Two	929,558		929,558		879,188
Year Three	871,061		871,061		599,452
Year Four	566,840		566,840		367,200
Year Five	358,240		358,240		297,769
Prior	1,155,675		1,155,675		975,388
Revolving Loans	132,830		132,830		173,763
Ending balance	4,219,603		4,219,603		4,232,191
Current period gross charge-offs
Current Fiscal Year			1,488
Year Two			2,164
Year Three			1,101
Year Four			437
Year Five			12
Prior			113
Revolving Loans			0
Total	2,904	0	5,315	185
Real estate loans: | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	196,419		196,419		920,189
Year Two	900,521		900,521		863,901
Year Three	838,517		838,517		591,440
Year Four	563,675		563,675		363,391
Year Five	355,326		355,326		296,103
Prior	1,147,158		1,147,158		966,854
Revolving Loans	71,125		71,125		73,383
Ending balance	4,072,741		4,072,741		4,075,261
Real estate loans: | Multifamily | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	86,526		86,526		632,613
Year Two	617,861		617,861		676,370
Year Three	652,903		652,903		500,069
Year Four	470,913		470,913		255,374
Year Five	250,844		250,844		208,335
Prior	702,493		702,493		551,297
Revolving Loans	601		601		521
Ending balance	2,782,141		2,782,141		2,824,579
Real estate loans: | Multifamily | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	86,526		86,526		632,613
Year Two	617,861		617,861		676,370
Year Three	652,903		652,903		500,069
Year Four	470,913		470,913		255,374
Year Five	250,844		250,844		204,810
Prior	693,124		693,124		545,335
Revolving Loans	601		601		521
Ending balance	2,772,772		2,772,772		2,815,092
Real estate loans: | Multifamily | Special mention | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	331		331
Revolving Loans	0		0
Ending balance	331		331
Real estate loans: | Multifamily | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		3,525
Prior	9,038		9,038		5,962
Revolving Loans	0		0		0
Ending balance	9,038		9,038		9,487
Real estate loans: | Commercial mortgage | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	84,267		84,267		216,510
Year Two	212,795		212,795		157,993
Year Three	156,104		156,104		68,215
Year Four	66,719		66,719		90,644
Year Five	88,529		88,529		72,512
Prior	322,130		322,130		291,711
Revolving Loans	2,443		2,443		1,664
Ending balance	932,987		932,987		899,249
Real estate loans: | Commercial mortgage | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	84,267		84,267		213,621
Year Two	209,944		209,944		147,419
Year Three	156,104		156,104		68,215
Year Four	66,719		66,719		90,644
Year Five	88,529		88,529		72,512
Prior	310,461		310,461		275,606
Revolving Loans	2,143		2,143		1,664
Ending balance	918,167		918,167		869,681
Real estate loans: | Commercial mortgage | Special mention | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	722		722		4,852
Revolving Loans	0		0		0
Ending balance	722		722		4,852
Real estate loans: | Commercial mortgage | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		2,889
Year Two	2,851		2,851		10,574
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	10,947		10,947		11,253
Revolving Loans	300		300		0
Ending balance	14,098		14,098		24,716
Real estate loans: | One-to-four family residential mortgage | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	6,226		6,226		26,432
Year Two	27,036		27,036		12,340
Year Three	12,115		12,115		8,623
Year Four	8,435		8,435		10,057
Year Five	9,138		9,138		7,227
Prior	100,623		100,623		108,261
Revolving Loans	952		952		1,006
Ending balance	164,525		164,525		173,946
Current period gross charge-offs
Total	0	0	0	0
Real estate loans: | One-to-four family residential mortgage | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	6,226		6,226		26,432
Year Two	27,036		27,036		12,340
Year Three	12,115		12,115		8,623
Year Four	8,435		8,435		10,057
Year Five	9,138		9,138		7,227
Prior	99,554		99,554		105,787
Revolving Loans	952		952		1,006
Ending balance	163,456		163,456		171,472
Real estate loans: | One-to-four family residential mortgage | Special mention | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	352		352		1,716
Revolving Loans	0		0		0
Ending balance	352		352		1,716
Real estate loans: | One-to-four family residential mortgage | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	717		717		758
Revolving Loans	0		0		0
Ending balance	717		717		758
Real estate loans: | Home equity and lines of credit | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	18,647		18,647		36,513
Year Two	34,510		34,510		16,053
Year Three	15,670		15,670		8,198
Year Four	7,357		7,357		6,040
Year Five	5,602		5,602		4,532
Prior	14,534		14,534		11,680
Revolving Loans	64,478		64,478		69,539
Ending balance	160,798		160,798		152,555
Current period gross charge-offs
Total	0	0	0	0
Real estate loans: | Home equity and lines of credit | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	18,647		18,647		36,513
Year Two	34,510		34,510		16,053
Year Three	15,648		15,648		8,198
Year Four	7,357		7,357		5,948
Year Five	5,512		5,512		4,484
Prior	14,314		14,314		11,315
Revolving Loans	64,478		64,478		69,539
Ending balance	160,466		160,466		152,050
Real estate loans: | Home equity and lines of credit | Special mention | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	68		68		70
Revolving Loans	0		0		0
Ending balance	68		68		70
Real estate loans: | Home equity and lines of credit | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	22		22		0
Year Four	0		0		92
Year Five	90		90		48
Prior	152		152		295
Revolving Loans	0		0		0
Ending balance	264		264		435
Real estate loans: | Construction and land | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	753		753		8,121
Year Two	8,319		8,319		1,145
Year Three	1,725		1,725		6,335
Year Four	10,251		10,251		1,276
Year Five	1,213		1,213		3,497
Prior	7,378		7,378		3,905
Revolving Loans	2,651		2,651		653
Ending balance	32,290		32,290		24,932
Current period gross charge-offs
Total	0	0	0	0
Real estate loans: | Construction and land | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	753		753		8,121
Year Two	8,319		8,319		1,145
Year Three	1,725		1,725		6,335
Year Four	10,251		10,251		1,276
Year Five	1,213		1,213		1,427
Prior	7,378		7,378		3,905
Revolving Loans	2,651		2,651		653
Ending balance	32,290		32,290		22,862
Real estate loans: | Construction and land | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year					0
Year Two					0
Year Three					0
Year Four					0
Year Five					2,070
Prior					0
Revolving Loans					0
Ending balance					2,070
Commercial and industrial | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	7,030		7,030		17,232
Year Two	29,037		29,037		15,287
Year Three	32,544		32,544		7,898
Year Four	3,109		3,109		3,804
Year Five	2,914		2,914		1,660
Prior	8,503		8,503		8,513
Revolving Loans	61,651		61,651		100,306
Ending balance	144,788		144,788		154,700
Current period gross charge-offs
Current Fiscal Year			1,488
Year Two			2,164
Year Three			1,101
Year Four			437
Year Five			12
Prior			113
Revolving Loans			0
Total	2,904	0	5,315	185
Commercial and industrial | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	7,025		7,025		16,941
Year Two	27,846		27,846		14,805
Year Three	18,348		18,348		7,754
Year Four	2,932		2,932		3,754
Year Five	2,818		2,818		1,460
Prior	8,032		8,032		8,172
Revolving Loans	61,651		61,651		98,969
Ending balance	128,652		128,652		151,855
Commercial and industrial | Special mention | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0		0
Year Two	250		250		0
Year Three	0		0		48
Year Four	61		61		0
Year Five	0		0		0
Prior	106		106		124
Revolving Loans	0		0		214
Ending balance	417		417		386
Commercial and industrial | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	5		5		291
Year Two	941		941		482
Year Three	14,196		14,196		96
Year Four	116		116		50
Year Five	96		96		200
Prior	365		365		217
Revolving Loans	0		0		1,123
Ending balance	15,719		15,719		2,459
Other loans | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,950		1,950		2,010
Year Two	0		0		0
Year Three	0		0		114
Year Four	56		56		5
Year Five	0		0		6
Prior	14		14		21
Revolving Loans	54		54		74
Ending balance	2,074		2,074		2,230
Current period gross charge-offs
Total	0	$ 0	0	$ 0
Other loans | Pass | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,950		1,950		2,010
Year Two	0		0		0
Year Three	0		0		114
Year Four	56		56		5
Year Five	0		0		6
Prior	14		14		21
Revolving Loans	44		44		74
Ending balance	2,064		2,064		$ 2,230
Other loans | Substandard | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0		0
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	0		0
Revolving Loans	10		10
Ending balance	$ 10		$ 10