Loans Receivable and Allowance for Credit Losses - Credit Risk Ratings , Vintage Years and/or Gross Write-offs for Loans Held-for-Investment by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	$ 48,918,048		$ 48,202,430
Revolving Loans Converted to Term Loans	199,820		191,523
Revolving Loans	11,249,959		11,460,495
Prior	6,897,179		4,261,980
Four Years before Current Fiscal Year	3,748,086		2,936,646
Three Years before Current Fiscal Year	4,596,433		3,871,740
Two Years before Current Fiscal Year	7,903,725		4,810,435
One Year before Current Fiscal Year	12,181,005		8,204,714
Converted to term loan		$ 0
Current Fiscal Year	2,141,841		12,464,897
Writeoff	273	$ 59
Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	48,003,978		47,306,450
Revolving Loans Converted to Term Loans	195,652		169,958
Revolving Loans	11,117,769		11,359,948
Prior	6,689,540		4,158,181
Four Years before Current Fiscal Year	3,652,587		2,786,218
Three Years before Current Fiscal Year	4,397,314		3,791,578
Two Years before Current Fiscal Year	7,737,183		4,590,045
One Year before Current Fiscal Year	12,072,397		8,084,723
Current Fiscal Year	2,141,536		12,365,799
Pass | Federal Housing Administration Loan
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Financing receivable, recorded investment, 90 days past due and still accruing, classified as pass	827		818
Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	821,772		797,272
Revolving Loans Converted to Term Loans	537		17,795
Revolving Loans	131,633		99,447
Prior	174,319		76,117
Four Years before Current Fiscal Year	92,190		142,072
Three Years before Current Fiscal Year	187,595		76,486
Two Years before Current Fiscal Year	145,395		208,970
One Year before Current Fiscal Year	90,098		96,150
Current Fiscal Year	5		80,235
Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	92,298		98,708
Revolving Loans Converted to Term Loans	3,631		3,770
Revolving Loans	557		1,100
Prior	33,320		27,682
Four Years before Current Fiscal Year	3,309		8,356
Three Years before Current Fiscal Year	11,524		3,676
Two Years before Current Fiscal Year	21,147		11,420
One Year before Current Fiscal Year	18,510		23,841
Current Fiscal Year	300		18,863
YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	185
One Year before Current Fiscal Year	68
Two Years before Current Fiscal Year	72
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	40
Revolving Loans Converted to Term Loans	0
Writeoff	1,924
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	1,559
HELOCs
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Converted to term loan	5,100
Commercial lending
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	35,074,650		34,780,453
Revolving Loans Converted to Term Loans	76,132		59,273
Revolving Loans	9,376,740		9,462,895
Prior	4,607,113		2,719,920
Four Years before Current Fiscal Year	2,664,474		2,111,867
Three Years before Current Fiscal Year	2,855,597		2,761,676
Two Years before Current Fiscal Year	5,486,147		3,020,575
One Year before Current Fiscal Year	8,657,400		5,745,996
Converted to term loan	12,200
Current Fiscal Year	1,351,047		8,898,251
Commercial lending | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	185
One Year before Current Fiscal Year	68
Two Years before Current Fiscal Year	72
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Writeoff	1,884
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	1,559
Commercial lending | Commercial and industrial (“C&I”)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	15,641,840		15,711,095
Revolving Loans Converted to Term Loans	20,446		20,548
Revolving Loans	9,190,637		9,275,389
Prior	276,340		120,853
Four Years before Current Fiscal Year	367,506		170,234
Three Years before Current Fiscal Year	562,303		426,477
Two Years before Current Fiscal Year	1,876,052		682,520
One Year before Current Fiscal Year	2,673,429		2,092,308
Current Fiscal Year	675,127		2,922,766
Commercial lending | Commercial and industrial (“C&I”) | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	15,226,965		15,339,612
Revolving Loans Converted to Term Loans	20,446		20,548
Revolving Loans	9,060,947		9,177,401
Prior	253,687		97,605
Four Years before Current Fiscal Year	333,681		143,970
Three Years before Current Fiscal Year	521,410		392,013
Two Years before Current Fiscal Year	1,783,684		623,026
One Year before Current Fiscal Year	2,578,285		2,053,215
Current Fiscal Year	674,825		2,831,834
Commercial lending | Commercial and industrial (“C&I”) | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	371,128		321,055
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	129,690		97,988
Prior	9,511		12,933
Four Years before Current Fiscal Year	33,825		20,646
Three Years before Current Fiscal Year	30,558		34,221
Two Years before Current Fiscal Year	90,595		48,761
One Year before Current Fiscal Year	76,947		34,296
Current Fiscal Year	2		72,210
Commercial lending | Commercial and industrial (“C&I”) | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	43,747		50,428
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	13,142		10,315
Four Years before Current Fiscal Year	0		5,618
Three Years before Current Fiscal Year	10,335		243
Two Years before Current Fiscal Year	1,773		10,733
One Year before Current Fiscal Year	18,197		4,797
Current Fiscal Year	300		18,722
Commercial lending | Commercial and industrial (“C&I”) | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	185
One Year before Current Fiscal Year	68
Two Years before Current Fiscal Year	72
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Writeoff	1,878
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	1,553
Commercial lending | CRE
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	14,019,136		13,857,870
Revolving Loans Converted to Term Loans	54,385		38,725
Revolving Loans	164,763		167,108
Prior	3,323,202		1,946,298
Four Years before Current Fiscal Year	1,779,596		1,562,842
Three Years before Current Fiscal Year	1,626,169		1,811,774
Two Years before Current Fiscal Year	2,459,002		1,664,574
One Year before Current Fiscal Year	4,143,268		2,484,251
Current Fiscal Year	468,751		4,182,298
Commercial lending | CRE | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	13,627,520		13,429,540
Revolving Loans Converted to Term Loans	54,385		22,009
Revolving Loans	163,308		165,653
Prior	3,216,726		1,909,925
Four Years before Current Fiscal Year	1,724,371		1,471,710
Three Years before Current Fiscal Year	1,470,520		1,771,679
Two Years before Current Fiscal Year	2,386,362		1,505,150
One Year before Current Fiscal Year	4,143,097		2,404,634
Current Fiscal Year	468,751		4,178,780
Commercial lending | CRE | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	372,348		405,086
Revolving Loans Converted to Term Loans	0		16,716
Revolving Loans	1,455		1,455
Prior	106,071		32,173
Four Years before Current Fiscal Year	55,225		91,132
Three Years before Current Fiscal Year	155,649		40,095
Two Years before Current Fiscal Year	53,948		159,424
One Year before Current Fiscal Year	0		60,573
Current Fiscal Year	0		3,518
Commercial lending | CRE | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	19,268		23,244
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	405		4,200
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	18,692		0
One Year before Current Fiscal Year	171		19,044
Current Fiscal Year	0		0
Commercial lending | CRE | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0
One Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	0
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Writeoff	6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	6
Commercial lending | Real estate loan | Multifamily residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	4,682,280		4,573,068
Revolving Loans Converted to Term Loans	1,301		0
Revolving Loans	9,253		11,325
Prior	982,988		652,538
Four Years before Current Fiscal Year	516,127		354,320
Three Years before Current Fiscal Year	633,118		520,321
Two Years before Current Fiscal Year	882,113		641,677
One Year before Current Fiscal Year	1,498,094		892,598
Current Fiscal Year	159,286		1,500,289
Commercial lending | Real estate loan | Pass | Multifamily residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	4,650,257		4,540,840
Revolving Loans Converted to Term Loans	1,301		0
Revolving Loans	9,253		11,325
Prior	951,669		625,293
Four Years before Current Fiscal Year	515,423		350,044
Three Years before Current Fiscal Year	633,118		519,614
Two Years before Current Fiscal Year	882,113		641,677
One Year before Current Fiscal Year	1,498,094		892,598
Current Fiscal Year	159,286		1,500,289
Commercial lending | Real estate loan | Criticized (accrual) | Multifamily residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	31,864		32,059
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	31,160		27,076
Four Years before Current Fiscal Year	704		4,276
Three Years before Current Fiscal Year	0		707
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	0		0
Current Fiscal Year	0		0
Commercial lending | Real estate loan | Criticized (nonaccrual) | Multifamily residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	159		169
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	159		169
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	0		0
Current Fiscal Year	0		0
Commercial lending | Construction and land
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	731,394		638,420
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	12,087		9,073
Prior	24,583		231
Four Years before Current Fiscal Year	1,245		24,471
Three Years before Current Fiscal Year	34,007		3,104
Two Years before Current Fiscal Year	268,980		31,804
One Year before Current Fiscal Year	342,609		276,839
Current Fiscal Year	47,883		292,898
Commercial lending | Construction and land | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	696,671		612,250
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	12,087		9,073
Prior	3,011		231
Four Years before Current Fiscal Year	1,245		2,805
Three Years before Current Fiscal Year	34,007		3,104
Two Years before Current Fiscal Year	268,980		31,804
One Year before Current Fiscal Year	329,458		276,839
Current Fiscal Year	47,883		288,394
Commercial lending | Construction and land | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	34,723		26,170
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	21,572		0
Four Years before Current Fiscal Year	0		21,666
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	13,151		0
Current Fiscal Year	0		4,504
Commercial lending | Construction and land | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	0		0
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	0		0
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	0		0
Current Fiscal Year	0		0
Commercial lending | Total CRE
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	19,432,810		19,069,358
Revolving Loans Converted to Term Loans	55,686		38,725
Revolving Loans	186,103		187,506
Prior	4,330,773		2,599,067
Four Years before Current Fiscal Year	2,296,968		1,941,633
Three Years before Current Fiscal Year	2,293,294		2,335,199
Two Years before Current Fiscal Year	3,610,095		2,338,055
One Year before Current Fiscal Year	5,983,971		3,653,688
Current Fiscal Year	675,920		5,975,485
Commercial lending | Total CRE | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0
One Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	0
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Writeoff	6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	6
Consumer lending
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	13,843,398		13,421,977
Revolving Loans Converted to Term Loans	123,688		132,250
Revolving Loans	1,873,219		1,997,600
Prior	2,290,066		1,542,060
Four Years before Current Fiscal Year	1,083,612		824,779
Three Years before Current Fiscal Year	1,740,836		1,110,064
Two Years before Current Fiscal Year	2,417,578		1,789,860
One Year before Current Fiscal Year	3,523,605		2,458,718
Current Fiscal Year	790,794		3,566,646
Consumer lending | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0
One Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	0
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	40
Revolving Loans Converted to Term Loans	0
Writeoff	40
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	0
Consumer lending | Real estate loan | Single-family residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	11,786,998		11,223,027
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	2,264,375		1,512,448
Four Years before Current Fiscal Year	1,081,192		823,237
Three Years before Current Fiscal Year	1,730,402		1,106,630
Two Years before Current Fiscal Year	2,416,029		1,776,685
One Year before Current Fiscal Year	3,505,098		2,454,992
Current Fiscal Year	789,902		3,549,035
Consumer lending | Real estate loan | Pass | Single-family residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	11,760,387		11,197,795
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	2,246,626		1,500,359
Four Years before Current Fiscal Year	1,075,516		817,164
Three Years before Current Fiscal Year	1,728,663		1,101,965
Two Years before Current Fiscal Year	2,414,724		1,775,696
One Year before Current Fiscal Year	3,504,956		2,453,717
Current Fiscal Year	789,902		3,548,894
Consumer lending | Real estate loan | Criticized (accrual) | Single-family residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	6,898		11,810
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	3,100		3,935
Four Years before Current Fiscal Year	2,436		4,352
Three Years before Current Fiscal Year	733		1,463
Two Years before Current Fiscal Year	629		785
One Year before Current Fiscal Year	0		1,275
Current Fiscal Year	0		0
Consumer lending | Real estate loan | Criticized (nonaccrual) | Single-family residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	19,713		13,422
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	14,649		8,154
Four Years before Current Fiscal Year	3,240		1,721
Three Years before Current Fiscal Year	1,006		3,202
Two Years before Current Fiscal Year	676		204
One Year before Current Fiscal Year	142		0
Current Fiscal Year	0		141
Consumer lending | HELOCs
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	1,988,881		2,122,655
Revolving Loans Converted to Term Loans	123,688		132,250
Revolving Loans	1,836,138		1,959,697
Prior	18,462		13,804
Four Years before Current Fiscal Year	2,420		1,542
Three Years before Current Fiscal Year	5,078		3,434
Two Years before Current Fiscal Year	1,412		7,819
One Year before Current Fiscal Year	1,683		3,589
Current Fiscal Year	0		520
Consumer lending | HELOCs | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	1,975,028		2,110,220
Revolving Loans Converted to Term Loans	119,520		127,401
Revolving Loans	1,835,459		1,958,692
Prior	10,592		8,960
Four Years before Current Fiscal Year	2,351		525
Three Years before Current Fiscal Year	4,240		3,203
Two Years before Current Fiscal Year	1,183		7,336
One Year before Current Fiscal Year	1,683		3,583
Current Fiscal Year	0		520
Consumer lending | HELOCs | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	4,808		1,089
Revolving Loans Converted to Term Loans	537		1,079
Revolving Loans	488		4
Prior	2,905		0
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	655		0
Two Years before Current Fiscal Year	223		0
One Year before Current Fiscal Year	0		6
Current Fiscal Year	0		0
Consumer lending | HELOCs | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	9,045		11,346
Revolving Loans Converted to Term Loans	3,631		3,770
Revolving Loans	191		1,001
Prior	4,965		4,844
Four Years before Current Fiscal Year	69		1,017
Three Years before Current Fiscal Year	183		231
Two Years before Current Fiscal Year	6		483
One Year before Current Fiscal Year	0		0
Current Fiscal Year	0		0
Consumer lending | Total residential mortgage
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	13,775,879		13,345,682
Revolving Loans Converted to Term Loans	123,688		132,250
Revolving Loans	1,836,138		1,959,697
Prior	2,282,837		1,526,252
Four Years before Current Fiscal Year	1,083,612		824,779
Three Years before Current Fiscal Year	1,735,480		1,110,064
Two Years before Current Fiscal Year	2,417,441		1,784,504
One Year before Current Fiscal Year	3,506,781		2,458,581
Current Fiscal Year	789,902		3,549,555
Consumer lending | Other consumer
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	67,519		76,295
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	37,081		37,903
Prior	7,229		15,808
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	5,356		0
Two Years before Current Fiscal Year	137		5,356
One Year before Current Fiscal Year	16,824		137
Current Fiscal Year	892		17,091
Consumer lending | Other consumer | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	67,150		76,193
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	36,715		37,804
Prior	7,229		15,808
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	5,356		0
Two Years before Current Fiscal Year	137		5,356
One Year before Current Fiscal Year	16,824		137
Current Fiscal Year	889		17,088
Consumer lending | Other consumer | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	3		3
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	0		0
Prior	0		0
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	0		0
Current Fiscal Year	3		3
Consumer lending | Other consumer | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Loans held-for-investment	366		99
Revolving Loans Converted to Term Loans	0		0
Revolving Loans	366		99
Prior	0		0
Four Years before Current Fiscal Year	0		0
Three Years before Current Fiscal Year	0		0
Two Years before Current Fiscal Year	0		0
One Year before Current Fiscal Year	0		0
Current Fiscal Year	0		$ 0
Consumer lending | Other consumer | YTD gross write-offs (3)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0
One Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	0
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Revolving Loans	40
Revolving Loans Converted to Term Loans	0
Writeoff	40
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff	$ 0