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		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 3,991,529		$ 4,022,224
Current-period gross charge-offs
Total	3,098	$ 950
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	33,385		115,930
Year Two	113,788		227,102
Year Three	224,425		869,173
Year Four	855,922		819,284
Year Five	807,597		544,689
Prior	1,784,054		1,279,905
Revolving Loans	163,315		156,968
Total	3,982,486		4,013,051
Current-period gross charge-offs
Current Fiscal Year	0		0
Year Two	0		387
Year Three	498		3,249
Year Four	1,467		2,966
Year Five	821		73
Prior	312		334
Revolving Loans	0		0
Total	3,098	950	7,009
Real estate loans: | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	29,123		95,607
Year Two	95,995		210,831
Year Three	209,028		848,649
Year Four	837,246		804,297
Year Five	794,135		541,640
Prior	1,775,135		1,273,078
Revolving Loans	78,280		73,359
Total	3,818,942		3,847,461
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	12,328		4,881
Year Two	4,866		86,169
Year Three	85,808		594,887
Year Four	586,344		630,083
Year Five	626,283		451,086
Prior	1,251,839		829,885
Revolving Loans	445		493
Total	2,567,913		2,597,484
Current-period gross charge-offs
Current Fiscal Year			0
Year Two			0
Year Three			0
Year Four			0
Year Five			0
Prior			136
Revolving Loans			0
Total			136
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	12,328		4,881
Year Two	4,866		86,169
Year Three	85,808		594,887
Year Four	586,344		628,886
Year Five	625,094		449,955
Prior	1,239,518		819,582
Revolving Loans	445		493
Total	2,554,403		2,584,853
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		1,197
Year Five	1,189		1,131
Prior	3,566		1,445
Revolving Loans	0		0
Total	4,755		3,773
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
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	8,755		8,858
Revolving Loans	0		0
Total	8,755		8,858
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	8,601		63,034
Year Two	62,733		87,164
Year Three	86,743		195,575
Year Four	194,063		149,231
Year Five	142,738		63,915
Prior	386,021		329,389
Revolving Loans	1,701		1,493
Total	882,600		889,801
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	8,601		63,034
Year Two	62,733		87,164
Year Three	86,743		195,575
Year Four	194,063		149,231
Year Five	142,738		61,214
Prior	367,230		309,280
Revolving Loans	1,410		1,200
Total	863,518		866,698
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
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		2,701
Prior	8,084		9,297
Revolving Loans	0		0
Total	8,084		11,998
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
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	10,707		10,812
Revolving Loans	291		293
Total	10,998		11,105
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	592		8,929
Year Two	8,867		6,597
Year Three	6,568		23,452
Year Four	22,429		11,728
Year Five	11,648		6,547
Prior	96,539		92,044
Revolving Loans	148		920
Total	146,791		150,217
Current-period gross charge-offs
Total	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	592		8,929
Year Two	8,867		6,597
Year Three	6,568		23,452
Year Four	22,429		11,728
Year Five	11,648		6,547
Prior	95,164		91,404
Revolving Loans	148		920
Total	145,416		149,577
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
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	1,375		640
Revolving Loans	0		0
Total	1,375		640
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	4,827		15,231
Year Two	14,899		19,647
Year Three	18,679		32,454
Year Four	31,483		12,630
Year Five	12,841		6,522
Prior	22,639		17,125
Revolving Loans	75,986		70,453
Total	181,354		174,062
Current-period gross charge-offs
Total	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	4,827		15,231
Year Two	14,899		19,647
Year Three	18,679		31,378
Year Four	30,410		12,209
Year Five	12,421		6,499
Prior	22,459		16,966
Revolving Loans	75,986		70,453
Total	179,681		172,383
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
Year Two	0		0
Year Three	0		68
Year Four	67		0
Year Five	0		0
Prior	0		0
Revolving Loans	0		0
Total	67		68
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
Year Two	0		0
Year Three	0		1,008
Year Four	1,006		421
Year Five	420		23
Prior	180		159
Revolving Loans	0		0
Total	1,606		1,611
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	2,775		3,532
Year Two	4,630		11,254
Year Three	11,230		2,281
Year Four	2,927		625
Year Five	625		13,570
Prior	18,097		4,635
Revolving Loans	0		0
Total	40,284		35,897
Current-period gross charge-offs
Total	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	2,775		3,532
Year Two	4,630		11,254
Year Three	11,230		2,281
Year Four	2,927		625
Year Five	625		13,570
Prior	18,097		4,635
Revolving Loans	0		0
Total	40,284		35,897
Commercial and industrial | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	2,903		18,227
Year Two	17,793		16,271
Year Three	15,397		20,524
Year Four	18,676		14,987
Year Five	13,462		3,049
Prior	8,903		6,811
Revolving Loans	84,999		83,556
Total	162,133		163,425
Current-period gross charge-offs
Current Fiscal Year	0		0
Year Two	0		387
Year Three	498		3,249
Year Four	1,467		2,966
Year Five	821		73
Prior	312		198
Revolving Loans	0		0
Total	3,098	950	6,873
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	2,903		15,733
Year Two	15,297		14,768
Year Three	14,438		19,043
Year Four	17,375		13,539
Year Five	11,737		2,977
Prior	8,550		6,680
Revolving Loans	84,167		82,552
Total	154,467		155,292
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
Year Two	0		770
Year Three	717		264
Year Four	0		168
Year Five	0		0
Prior	0		0
Revolving Loans	0		0
Total	717		1,202
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	0		2,494
Year Two	2,496		733
Year Three	242		1,217
Year Four	1,301		1,280
Year Five	1,725		72
Prior	353		131
Revolving Loans	832		1,004
Total	6,949		6,931
Other loans | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,359		2,096
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	16		16
Revolving Loans	36		53
Total	1,411		2,165
Current-period gross charge-offs
Total	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	1,359		2,096
Year Two	0		0
Year Three	0		0
Year Four	0		0
Year Five	0		0
Prior	11		11
Revolving Loans	36		53
Total	1,406		2,160
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	5		5
Revolving Loans	0		0
Total	$ 5		$ 5