Loans Receivable and Allowance for Credit Losses (Aging Analysis on Loans Held-for-Investment) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	$ 84,834	$ 93,181
Total	43,490,682	41,693,781
Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Total	43,340,559	41,555,745
Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Total	65,289	44,855
Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	46,045	31,091
Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	19,244	13,764
Commercial lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	61,600	68,965
Total	31,813,220	30,327,746
Commercial lending | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	51,773	59,023
Total	14,838,134	14,150,608
Commercial lending | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	9,404	9,498
Total	12,636,787	12,155,047
Commercial lending | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	423	444
Total	3,894,463	3,675,605
Commercial lending | Construction and land
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	0	0
Total	443,836	346,486
Commercial lending | Total CRE
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	9,827	9,942
Total	16,975,086	16,177,138
Commercial lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Total	31,719,866	30,238,648
Commercial lending | Current Accruing Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total	14,759,847	14,080,516
Commercial lending | Current Accruing Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total	12,624,346	12,141,827
Commercial lending | Current Accruing Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total	3,891,837	3,669,819
Commercial lending | Current Accruing Loans | Construction and land
Current, Past Due or Nonaccrual Loans
Total	443,836	346,486
Commercial lending | Current Accruing Loans | Total CRE
Current, Past Due or Nonaccrual Loans
Total	16,960,019	16,158,132
Commercial lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Total	31,754	20,133
Commercial lending | Total Accruing Past Due Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total	26,514	11,069
Commercial lending | Total Accruing Past Due Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total	3,037	3,722
Commercial lending | Total Accruing Past Due Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total	2,203	5,342
Commercial lending | Total Accruing Past Due Loans | Construction and land
Current, Past Due or Nonaccrual Loans
Total	0	0
Commercial lending | Total Accruing Past Due Loans | Total CRE
Current, Past Due or Nonaccrual Loans
Total	5,240	9,064
Commercial lending | Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	26,781	16,025
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total	23,082	6,983
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total	2,895	3,722
Commercial lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total	804	5,320
Commercial lending | Accruing Loans 30-59  Days Past Due | Construction and land
Current, Past Due or Nonaccrual Loans
Total	0	0
Commercial lending | Accruing Loans 30-59  Days Past Due | Total CRE
Current, Past Due or Nonaccrual Loans
Total	3,699	9,042
Commercial lending | Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	4,973	4,108
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total	3,432	4,086
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total	142	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total	1,399	22
Commercial lending | Accruing Loans 60-89  Days Past Due | Construction and land
Current, Past Due or Nonaccrual Loans
Total	0	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Total CRE
Current, Past Due or Nonaccrual Loans
Total	1,541	22
Consumer lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	23,234	24,216
Total	11,677,462	11,366,035
Consumer lending | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	16,385	15,720
Total	9,283,429	9,093,702
Consumer lending | HELOCs
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	6,812	8,444
Total	2,266,634	2,144,821
Consumer lending | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	23,197	24,164
Total	11,550,063	11,238,523
Consumer lending | Other consumer
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	37	52
Total	127,399	127,512
Consumer lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Total	11,620,693	11,317,097
Consumer lending | Current Accruing Loans | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total	9,240,375	9,059,222
Consumer lending | Current Accruing Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Total	2,253,750	2,130,523
Consumer lending | Current Accruing Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total	11,494,125	11,189,745
Consumer lending | Current Accruing Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Total	126,568	127,352
Consumer lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Total	33,535	24,722
Consumer lending | Total Accruing Past Due Loans | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total	26,669	18,760
Consumer lending | Total Accruing Past Due Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Total	6,072	5,854
Consumer lending | Total Accruing Past Due Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total	32,741	24,614
Consumer lending | Total Accruing Past Due Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Total	794	108
Consumer lending | Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	19,264	15,066
Consumer lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total	15,998	10,191
Consumer lending | Accruing Loans 30-59  Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Total	3,116	4,776
Consumer lending | Accruing Loans 30-59  Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total	19,114	14,967
Consumer lending | Accruing Loans 30-59  Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Total	150	99
Consumer lending | Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Total	14,271	9,656
Consumer lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total	10,671	8,569
Consumer lending | Accruing Loans 60-89  Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Total	2,956	1,078
Consumer lending | Accruing Loans 60-89  Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total	13,627	9,647
Consumer lending | Accruing Loans 60-89  Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Total	$ 644	$ 9