Loans Receivable and Allowance for Credit Losses (Aging Analysis on Loans Held-for-Investment) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	$ 133,160	$ 215,154
Total	40,481,705	38,390,955
Current Accruing Loans
Nonaccrual and Past Due Loans
Total	40,307,700	38,125,211
Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	40,845	50,590
Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	24,869	44,136
Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	15,976	6,454
Commercial lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	112,516	184,153
Total	29,367,013	28,440,027
Commercial lending | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	97,157	133,939
Total	13,831,649	13,631,726
Commercial lending | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	14,236	46,546
Total	11,818,065	11,174,611
Commercial lending | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,123	3,668
Total	3,340,378	3,033,998
Commercial lending | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0	0
Total	376,921	599,692
Commercial lending | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	15,359	50,214
Total	15,535,364	14,808,301
Commercial lending | Current Accruing Loans
Nonaccrual and Past Due Loans
Total	29,235,286	28,224,064
Commercial lending | Current Accruing Loans | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	13,717,788	13,488,070
Commercial lending | Current Accruing Loans | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	11,803,236	11,127,690
Commercial lending | Current Accruing Loans | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	3,337,341	3,028,512
Commercial lending | Current Accruing Loans | Construction and land
Nonaccrual and Past Due Loans
Total	376,921	579,792
Commercial lending | Current Accruing Loans | Total CRE
Nonaccrual and Past Due Loans
Total	15,517,498	14,735,994
Commercial lending | Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	19,211	31,810
Commercial lending | Total Accruing Past Due Loans | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	16,704	9,717
Commercial lending | Total Accruing Past Due Loans | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	593	375
Commercial lending | Total Accruing Past Due Loans | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	1,914	1,818
Commercial lending | Total Accruing Past Due Loans | Construction and land
Nonaccrual and Past Due Loans
Total	0	19,900
Commercial lending | Total Accruing Past Due Loans | Total CRE
Nonaccrual and Past Due Loans
Total	2,507	22,093
Commercial lending | Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	8,949	31,086
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	6,597	8,993
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	438	375
Commercial lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	1,914	1,818
Commercial lending | Accruing Loans 30-59  Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total	0	19,900
Commercial lending | Accruing Loans 30-59  Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total	2,352	22,093
Commercial lending | Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	10,262	724
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	10,107	724
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	155	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	0	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total	0	0
Commercial lending | Accruing Loans 60-89  Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total	155	0
Consumer lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	20,644	31,001
Total	11,114,692	9,950,928
Consumer lending | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	9,422	16,814
Total	9,021,801	8,185,953
Consumer lending | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	8,731	11,696
Total	1,963,622	1,601,716
Consumer lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	18,153	28,510
Total	10,985,423	9,787,669
Consumer lending | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	2,491	2,491
Total	129,269	163,259
Consumer lending | Current Accruing Loans
Nonaccrual and Past Due Loans
Total	11,072,414	9,901,147
Consumer lending | Current Accruing Loans | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	8,995,226	8,156,645
Consumer lending | Current Accruing Loans | HELOCs
Nonaccrual and Past Due Loans
Total	1,950,594	1,583,968
Consumer lending | Current Accruing Loans | Total residential mortgage
Nonaccrual and Past Due Loans
Total	10,945,820	9,740,613
Consumer lending | Current Accruing Loans | Other consumer
Nonaccrual and Past Due Loans
Total	126,594	160,534
Consumer lending | Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	21,634	18,780
Consumer lending | Total Accruing Past Due Loans | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	17,153	12,494
Consumer lending | Total Accruing Past Due Loans | HELOCs
Nonaccrual and Past Due Loans
Total	4,297	6,052
Consumer lending | Total Accruing Past Due Loans | Total residential mortgage
Nonaccrual and Past Due Loans
Total	21,450	18,546
Consumer lending | Total Accruing Past Due Loans | Other consumer
Nonaccrual and Past Due Loans
Total	184	234
Consumer lending | Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	15,920	13,050
Consumer lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	13,442	9,911
Consumer lending | Accruing Loans 30-59  Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total	2,298	2,922
Consumer lending | Accruing Loans 30-59  Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total	15,740	12,833
Consumer lending | Accruing Loans 30-59  Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total	180	217
Consumer lending | Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	5,714	5,730
Consumer lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	3,711	2,583
Consumer lending | Accruing Loans 60-89  Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total	1,999	3,130
Consumer lending | Accruing Loans 60-89  Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total	5,710	5,713
Consumer lending | Accruing Loans 60-89  Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total	$ 4	$ 17