Loans Receivable and Allowance for Credit Losses - Aging Analysis on Loans Held-for-Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	$ 82,543	$ 93,181
Loans held-for-investment	47,442,255	41,693,781
Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	47,310,099	41,555,745
Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	49,613	44,855
Accruing Loans 30-59 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	39,110	31,091
Accruing Loans 60-89 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,503	13,764
Commercial lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	59,197	68,965
Loans held-for-investment	34,314,425	30,327,746
Commercial lending | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	47,988	59,023
Loans held-for-investment	15,625,072	14,150,608
Commercial lending | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	11,035	9,498
Loans held-for-investment	13,573,157	12,155,047
Commercial lending | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	174	444
Loans held-for-investment	4,559,302	3,675,605
Commercial lending | Construction and land
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	0	0
Loans held-for-investment	556,894	346,486
Commercial lending | Total CRE
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	11,209	9,942
Loans held-for-investment	18,689,353	16,177,138
Commercial lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	34,232,850	30,238,648
Commercial lending | Current Accruing Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	15,556,124	14,080,516
Commercial lending | Current Accruing Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	13,561,499	12,141,827
Commercial lending | Current Accruing Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	4,558,333	3,669,819
Commercial lending | Current Accruing Loans | Construction and land
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	556,894	346,486
Commercial lending | Current Accruing Loans | Total CRE
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	18,676,726	16,158,132
Commercial lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	22,378	20,133
Commercial lending | Total Accruing Past Due Loans | Commercial and industrial (“C&I”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	20,960	11,069
Commercial lending | Total Accruing Past Due Loans | Commercial real estate (“CRE”)
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	623	3,722
Commercial lending | Total Accruing Past Due Loans | Real estate loan | Multifamily residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	795	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	1,418	9,064
Commercial lending | Accruing Loans 30-59 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	22,161	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	20,877	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	489	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	795	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	1,284	9,042
Commercial lending | Accruing Loans 60-89 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	217	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	83	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	134	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	134	22
Consumer lending
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	23,346	24,216
Loans held-for-investment	13,127,830	11,366,035
Consumer lending | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	12,741	15,720
Loans held-for-investment	10,855,345	9,093,702
Consumer lending | HELOCs
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	10,568	8,444
Loans held-for-investment	2,184,924	2,144,821
Consumer lending | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	23,309	24,164
Loans held-for-investment	13,040,269	11,238,523
Consumer lending | Other consumer
Current, Past Due or Nonaccrual Loans
Total Nonaccrual Loans	37	52
Loans held-for-investment	87,561	127,512
Consumer lending | Current Accruing Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	13,077,249	11,317,097
Consumer lending | Current Accruing Loans | Real estate loan | Single-family residential
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,820,365	9,059,222
Consumer lending | Current Accruing Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	2,169,440	2,130,523
Consumer lending | Current Accruing Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	12,989,805	11,189,745
Consumer lending | Current Accruing Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	87,444	127,352
Consumer lending | Total Accruing Past Due Loans
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	27,235	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	22,239	18,760
Consumer lending | Total Accruing Past Due Loans | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	4,916	5,854
Consumer lending | Total Accruing Past Due Loans | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	27,155	24,614
Consumer lending | Total Accruing Past Due Loans | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	80	108
Consumer lending | Accruing Loans 30-59 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	16,949	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	13,914	10,191
Consumer lending | Accruing Loans 30-59 Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	2,992	4,776
Consumer lending | Accruing Loans 30-59 Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	16,906	14,967
Consumer lending | Accruing Loans 30-59 Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	43	99
Consumer lending | Accruing Loans 60-89 Days Past Due
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,286	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	8,325	8,569
Consumer lending | Accruing Loans 60-89 Days Past Due | HELOCs
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	1,924	1,078
Consumer lending | Accruing Loans 60-89 Days Past Due | Total residential mortgage
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	10,249	9,647
Consumer lending | Accruing Loans 60-89 Days Past Due | Other consumer
Current, Past Due or Nonaccrual Loans
Loans held-for-investment	$ 37	$ 9