Loans Receivable and Allowance for Credit Losses - Credit Risk Ratings and/or Vintage Years for Loans Held-for-Investment by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	$ 7,514,619	$ 10,680,884
One Year before Current Fiscal Year	9,462,023	6,294,357
Two Years before Current Fiscal Year	5,431,280	5,104,045
Three Years before Current Fiscal Year	4,417,353	3,678,223
Four Years before Current Fiscal Year	3,228,387	2,400,331
Prior	5,170,465	3,686,038
Revolving Loans	11,056,032	9,612,862
Revolving Loans Converted to Term Loans	221,917	237,041
Total	46,502,076	41,693,781
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	1,200	1,600
Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	7,441,743	10,487,630
One Year before Current Fiscal Year	9,298,963	6,171,008
Two Years before Current Fiscal Year	5,287,308	5,019,097
Three Years before Current Fiscal Year	4,280,439	3,553,784
Four Years before Current Fiscal Year	3,043,927	2,329,521
Prior	4,975,025	3,569,404
Revolving Loans	10,951,399	9,497,636
Revolving Loans Converted to Term Loans	200,631	232,645
Total	45,479,435	40,860,725
Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	69,634	159,448
One Year before Current Fiscal Year	153,722	120,557
Two Years before Current Fiscal Year	127,048	82,632
Three Years before Current Fiscal Year	133,916	119,845
Four Years before Current Fiscal Year	169,863	48,919
Prior	159,433	94,146
Revolving Loans	102,894	115,174
Revolving Loans Converted to Term Loans	17,421	708
Total	933,931	741,429
Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	3,242	33,806
One Year before Current Fiscal Year	9,338	2,792
Two Years before Current Fiscal Year	16,924	2,316
Three Years before Current Fiscal Year	2,998	4,594
Four Years before Current Fiscal Year	14,597	21,891
Prior	36,007	22,488
Revolving Loans	1,739	52
Revolving Loans Converted to Term Loans	3,865	3,688
Total	88,710	91,627
Commercial lending
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	5,528,949	8,046,445
One Year before Current Fiscal Year	6,876,455	4,177,452
Two Years before Current Fiscal Year	3,511,628	3,721,211
Three Years before Current Fiscal Year	3,217,750	2,590,956
Four Years before Current Fiscal Year	2,316,405	1,622,234
Prior	3,469,021	2,486,373
Revolving Loans	8,923,437	7,647,844
Revolving Loans Converted to Term Loans	59,781	35,231
Total	33,903,426	30,327,746
Commercial lending | Commercial and industrial (“C&I”)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,700,425	4,026,214
One Year before Current Fiscal Year	2,996,403	1,253,234
Two Years before Current Fiscal Year	835,989	701,797
Three Years before Current Fiscal Year	556,885	239,265
Four Years before Current Fiscal Year	199,955	156,829
Prior	301,287	245,775
Revolving Loans	8,757,698	7,498,652
Revolving Loans Converted to Term Loans	28,475	28,842
Total	15,377,117	14,150,608
Commercial lending | Commercial and industrial (“C&I”) | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,632,575	3,911,722
One Year before Current Fiscal Year	2,948,526	1,133,085
Two Years before Current Fiscal Year	769,887	629,007
Three Years before Current Fiscal Year	524,311	187,195
Four Years before Current Fiscal Year	170,119	132,392
Prior	270,405	225,326
Revolving Loans	8,656,225	7,383,485
Revolving Loans Converted to Term Loans	28,475	28,842
Total	15,000,523	13,631,054
Commercial lending | Commercial and industrial (“C&I”) | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	64,608	85,036
One Year before Current Fiscal Year	43,748	117,357
Two Years before Current Fiscal Year	50,746	72,277
Three Years before Current Fiscal Year	32,574	51,553
Four Years before Current Fiscal Year	24,206	15,136
Prior	19,222	4,005
Revolving Loans	101,437	115,167
Revolving Loans Converted to Term Loans	0	0
Total	336,541	460,531
Commercial lending | Commercial and industrial (“C&I”) | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	3,242	29,456
One Year before Current Fiscal Year	4,129	2,792
Two Years before Current Fiscal Year	15,356	513
Three Years before Current Fiscal Year	0	517
Four Years before Current Fiscal Year	5,630	9,301
Prior	11,660	16,444
Revolving Loans	36	0
Revolving Loans Converted to Term Loans	0	0
Total	40,053	59,023
Commercial lending | Commercial real estate (“CRE”)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	2,643,050	2,867,598
One Year before Current Fiscal Year	2,679,840	2,093,703
Two Years before Current Fiscal Year	1,885,049	2,239,696
Three Years before Current Fiscal Year	2,007,262	1,884,558
Four Years before Current Fiscal Year	1,699,430	1,150,285
Prior	2,468,373	1,784,150
Revolving Loans	152,438	128,668
Revolving Loans Converted to Term Loans	31,306	6,389
Total	13,566,748	12,155,047
Commercial lending | Commercial real estate (“CRE”) | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	2,638,027	2,792,193
One Year before Current Fiscal Year	2,565,665	2,090,503
Two Years before Current Fiscal Year	1,815,298	2,230,520
Three Years before Current Fiscal Year	1,907,721	1,863,481
Four Years before Current Fiscal Year	1,598,242	1,120,682
Prior	2,358,965	1,727,862
Revolving Loans	150,983	128,668
Revolving Loans Converted to Term Loans	14,498	6,389
Total	13,049,399	11,960,298
Commercial lending | Commercial real estate (“CRE”) | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	5,023	71,055
One Year before Current Fiscal Year	109,974	3,200
Two Years before Current Fiscal Year	69,751	9,176
Three Years before Current Fiscal Year	99,541	21,077
Four Years before Current Fiscal Year	101,188	24,851
Prior	102,333	55,892
Revolving Loans	1,455	0
Revolving Loans Converted to Term Loans	16,808	0
Total	506,073	185,251
Commercial lending | Commercial real estate (“CRE”) | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	4,350
One Year before Current Fiscal Year	4,201	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	4,752
Prior	7,075	396
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	11,276	9,498
Commercial lending | Real estate loan | Multifamily residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,091,403	1,026,295
One Year before Current Fiscal Year	967,791	726,772
Two Years before Current Fiscal Year	687,577	689,174
Three Years before Current Fiscal Year	592,675	441,663
Four Years before Current Fiscal Year	391,832	315,120
Prior	699,125	456,057
Revolving Loans	13,301	20,524
Revolving Loans Converted to Term Loans	0	0
Total	4,443,704	3,675,605
Commercial lending | Real estate loan | Multifamily residential | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,091,403	1,026,295
One Year before Current Fiscal Year	967,791	726,772
Two Years before Current Fiscal Year	687,577	688,453
Three Years before Current Fiscal Year	591,961	419,319
Four Years before Current Fiscal Year	371,378	308,087
Prior	661,082	424,947
Revolving Loans	13,301	20,524
Revolving Loans Converted to Term Loans	0	0
Total	4,384,493	3,614,397
Commercial lending | Real estate loan | Multifamily residential | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year		721
Three Years before Current Fiscal Year	714	22,344
Four Years before Current Fiscal Year	20,454	7,033
Prior	36,577	30,666
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	57,745	60,764
Commercial lending | Real estate loan | Multifamily residential | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	1,466	444
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	1,466	444
Commercial lending | Construction and land
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	94,071	126,338
One Year before Current Fiscal Year	232,421	103,743
Two Years before Current Fiscal Year	103,013	90,544
Three Years before Current Fiscal Year	60,928	25,470
Four Years before Current Fiscal Year	25,188	0
Prior	236	391
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	515,857	346,486
Commercial lending | Construction and land | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	94,071	122,983
One Year before Current Fiscal Year	232,421	103,743
Two Years before Current Fiscal Year	98,608	90,544
Three Years before Current Fiscal Year	60,928	3,412
Four Years before Current Fiscal Year	3,332	0
Prior	236	391
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	489,596	321,073
Commercial lending | Construction and land | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	3,355
One Year before Current Fiscal Year		0
Two Years before Current Fiscal Year	4,405	0
Three Years before Current Fiscal Year	0	22,058
Four Years before Current Fiscal Year	21,856	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	26,261	25,413
Commercial lending | Construction and land | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	0	0
Commercial lending | Total CRE
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	3,828,524	4,020,231
One Year before Current Fiscal Year	3,880,052	2,924,218
Two Years before Current Fiscal Year	2,675,639	3,019,414
Three Years before Current Fiscal Year	2,660,865	2,351,691
Four Years before Current Fiscal Year	2,116,450	1,465,405
Prior	3,167,734	2,240,598
Revolving Loans	165,739	149,192
Revolving Loans Converted to Term Loans	31,306	6,389
Total	18,526,309	16,177,138
Consumer lending
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,985,670	2,634,439
One Year before Current Fiscal Year	2,585,568	2,116,905
Two Years before Current Fiscal Year	1,919,652	1,382,834
Three Years before Current Fiscal Year	1,199,603	1,087,267
Four Years before Current Fiscal Year	911,982	778,097
Prior	1,701,444	1,199,665
Revolving Loans	2,132,595	1,965,018
Revolving Loans Converted to Term Loans	162,136	201,810
Total	12,598,650	11,366,035
Consumer lending | Real estate loan | Single-family residential
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,983,527	2,616,958
One Year before Current Fiscal Year	2,565,374	2,108,370
Two Years before Current Fiscal Year	1,906,720	1,378,138
Three Years before Current Fiscal Year	1,198,130	1,085,732
Four Years before Current Fiscal Year	909,431	769,545
Prior	1,671,291	1,134,959
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	10,234,473	9,093,702
Consumer lending | Real estate loan | Single-family residential | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,983,527	2,616,958
One Year before Current Fiscal Year	2,565,374	2,108,370
Two Years before Current Fiscal Year	1,903,821	1,375,929
Three Years before Current Fiscal Year	1,194,265	1,079,030
Four Years before Current Fiscal Year	898,768	763,351
Prior	1,655,824	1,127,516
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	10,201,579	9,071,154
Consumer lending | Real estate loan | Single-family residential | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	2,146	458
Three Years before Current Fiscal Year	1,087	2,813
Four Years before Current Fiscal Year	2,159	1,899
Prior	1,301	3,212
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	6,693	8,382
Consumer lending | Real estate loan | Single-family residential | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	753	1,751
Three Years before Current Fiscal Year	2,778	3,889
Four Years before Current Fiscal Year	8,504	4,295
Prior	14,166	4,231
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	26,201	14,166
Consumer lending | HELOCs
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	929	648
One Year before Current Fiscal Year	7,122	3,277
Two Years before Current Fiscal Year	7,674	4,696
Three Years before Current Fiscal Year	1,473	1,535
Four Years before Current Fiscal Year	2,551	6,811
Prior	14,980	12,559
Revolving Loans	2,083,215	1,913,485
Revolving Loans Converted to Term Loans	162,136	201,810
Total	2,280,080	2,144,821
Consumer lending | HELOCs | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	929	648
One Year before Current Fiscal Year	6,114	3,277
Two Years before Current Fiscal Year	6,859	4,644
Three Years before Current Fiscal Year	1,253	1,347
Four Years before Current Fiscal Year	2,088	3,268
Prior	13,340	11,215
Revolving Loans	2,081,521	1,913,478
Revolving Loans Converted to Term Loans	157,658	197,414
Total	2,269,762	2,135,291
Consumer lending | HELOCs | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior		371
Revolving Loans	2	7
Revolving Loans Converted to Term Loans	613	708
Total	615	1,086
Consumer lending | HELOCs | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	1,008	0
Two Years before Current Fiscal Year	815	52
Three Years before Current Fiscal Year	220	188
Four Years before Current Fiscal Year	463	3,543
Prior	1,640	973
Revolving Loans	1,692	0
Revolving Loans Converted to Term Loans	3,865	3,688
Total	9,703	8,444
Consumer lending | Total residential mortgage
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,984,456	2,617,606
One Year before Current Fiscal Year	2,572,496	2,111,647
Two Years before Current Fiscal Year	1,914,394	1,382,834
Three Years before Current Fiscal Year	1,199,603	1,087,267
Four Years before Current Fiscal Year	911,982	776,356
Prior	1,686,271	1,147,518
Revolving Loans	2,083,215	1,913,485
Revolving Loans Converted to Term Loans	162,136	201,810
Total	12,514,553	11,238,523
Consumer lending | Other consumer
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,214	16,833
One Year before Current Fiscal Year	13,072	5,258
Two Years before Current Fiscal Year	5,258	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	1,741
Prior	15,173	52,147
Revolving Loans	49,380	51,533
Revolving Loans Converted to Term Loans	0	0
Total	84,097	127,512
Consumer lending | Other consumer | Pass
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	1,211	16,831
One Year before Current Fiscal Year	13,072	5,258
Two Years before Current Fiscal Year	5,258	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	1,741
Prior	15,173	52,147
Revolving Loans	49,369	51,481
Revolving Loans Converted to Term Loans	0	0
Total	84,083	127,458
Consumer lending | Other consumer | Criticized (accrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	3	2
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	3	2
Consumer lending | Other consumer | Criticized (nonaccrual)
Financing Receivable, Vintage Year/Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
One Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving Loans	11	52
Revolving Loans Converted to Term Loans	0	0
Total	$ 11	$ 52