Loans Receivable and Allowance for Credit Losses - Aging Analysis on Loans Held-for-Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	$ 89,935	$ 93,181
Loans held-for-investment	46,502,076	41,693,781
Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	46,372,850	41,555,745
Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	39,291	44,855
Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	31,442	31,091
Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	7,849	13,764
Commercial lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	52,795	68,965
Loans held-for-investment	33,903,426	30,327,746
Commercial lending | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	40,053	59,023
Loans held-for-investment	15,377,117	14,150,608
Commercial lending | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	11,276	9,498
Loans held-for-investment	13,566,748	12,155,047
Commercial lending | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	1,466	444
Loans held-for-investment	4,443,704	3,675,605
Commercial lending | Construction and land
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	0	0
Loans held-for-investment	515,857	346,486
Commercial lending | Total CRE
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	12,742	9,942
Loans held-for-investment	18,526,309	16,177,138
Commercial lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	33,839,019	30,238,648
Commercial lending | Current Accruing Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	15,326,934	14,080,516
Commercial lending | Current Accruing Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	13,554,820	12,141,827
Commercial lending | Current Accruing Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	4,441,408	3,669,819
Commercial lending | Current Accruing Loans | Construction and land
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	515,857	346,486
Commercial lending | Current Accruing Loans | Total CRE
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	18,512,085	16,158,132
Commercial lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	11,612	20,133
Commercial lending | Total Accruing Past Due Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,130	11,069
Commercial lending | Total Accruing Past Due Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	652	3,722
Commercial lending | Total Accruing Past Due Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	830	5,342
Commercial lending | Total Accruing Past Due Loans | Construction and land
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	0	0
Commercial lending | Total Accruing Past Due Loans | Total CRE
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	1,482	9,064
Commercial lending | Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	11,378	16,025
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,097	6,983
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	451	3,722
Commercial lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	830	5,320
Commercial lending | Accruing Loans 30-59  Days Past Due | Construction and land
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	0	0
Commercial lending | Accruing Loans 30-59  Days Past Due | Total CRE
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	1,281	9,042
Commercial lending | Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	234	4,108
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	33	4,086
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	201	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	0	22
Commercial lending | Accruing Loans 60-89  Days Past Due | Construction and land
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	0	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Total CRE
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	201	22
Consumer lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	37,140	24,216
Loans held-for-investment	12,598,650	11,366,035
Consumer lending | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	27,426	15,720
Loans held-for-investment	10,234,473	9,093,702
Consumer lending | HELOCs
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	9,703	8,444
Loans held-for-investment	2,280,080	2,144,821
Consumer lending | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	37,129	24,164
Loans held-for-investment	12,514,553	11,238,523
Consumer lending | Other consumer
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	11	52
Loans held-for-investment	84,097	127,512
Consumer lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	12,533,831	11,317,097
Consumer lending | Current Accruing Loans | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,186,333	9,059,222
Consumer lending | Current Accruing Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	2,263,510	2,130,523
Consumer lending | Current Accruing Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	12,449,843	11,189,745
Consumer lending | Current Accruing Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	83,988	127,352
Consumer lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	27,679	24,722
Consumer lending | Total Accruing Past Due Loans | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	20,714	18,760
Consumer lending | Total Accruing Past Due Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	6,867	5,854
Consumer lending | Total Accruing Past Due Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	27,581	24,614
Consumer lending | Total Accruing Past Due Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	98	108
Consumer lending | Accruing Loans 30-59  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	20,064	15,066
Consumer lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	13,718	10,191
Consumer lending | Accruing Loans 30-59  Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	6,254	4,776
Consumer lending | Accruing Loans 30-59  Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	19,972	14,967
Consumer lending | Accruing Loans 30-59  Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	92	99
Consumer lending | Accruing Loans 60-89  Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	7,615	9,656
Consumer lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	6,996	8,569
Consumer lending | Accruing Loans 60-89  Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	613	1,078
Consumer lending | Accruing Loans 60-89  Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	7,609	9,647
Consumer lending | Accruing Loans 60-89  Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	$ 6	$ 9