Loans Receivable and Allowance for Credit Losses (Aging Analysis on Loans Held-for-Investment) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	$ 197,790	$ 215,154
Total	40,071,499	38,390,955
Current Accruing Loans
Nonaccrual and Past Due Loans
Total	39,818,404	38,125,211
Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	55,305	50,590
Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	52,436	44,136
Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	2,869	6,454
Commercial lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	164,798	184,153
Total	29,182,304	28,440,027
Commercial lending | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	83,225	133,939
Total	13,790,461	13,631,726
Commercial lending | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	58,780	46,546
Total	11,711,369	11,174,611
Commercial lending | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	2,893	3,668
Total	3,219,796	3,033,998
Commercial lending | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	19,900	0
Total	460,678	599,692
Commercial lending | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	81,573	50,214
Total	15,391,843	14,808,301
Commercial lending | Current Accruing Loans
Nonaccrual and Past Due Loans
Total	28,980,913	28,224,064
Commercial lending | Current Accruing Loans | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	13,677,054	13,488,070
Commercial lending | Current Accruing Loans | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	11,647,942	11,127,690
Commercial lending | Current Accruing Loans | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	3,215,139	3,028,512
Commercial lending | Current Accruing Loans | Construction and land
Nonaccrual and Past Due Loans
Total	440,778	579,792
Commercial lending | Current Accruing Loans | Total CRE
Nonaccrual and Past Due Loans
Total	15,303,859	14,735,994
Commercial lending | Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	36,593	31,810
Commercial lending | Total Accruing Past Due Loans | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	30,182	9,717
Commercial lending | Total Accruing Past Due Loans | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	4,647	375
Commercial lending | Total Accruing Past Due Loans | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	1,764	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	6,411	22,093
Commercial lending | Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	36,559	31,086
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	30,148	8,993
Commercial lending | Accruing Loans 30-59  Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	4,647	375
Commercial lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total	1,764	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	6,411	22,093
Commercial lending | Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	34	724
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total	34	724
Commercial lending | Accruing Loans 60-89  Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total	0	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	0	0
Consumer lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	32,992	31,001
Total	10,889,195	9,950,928
Consumer lending | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	20,168	16,814
Total	8,869,370	8,185,953
Consumer lending | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	10,321	11,696
Total	1,872,166	1,601,716
Consumer lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	30,489	28,510
Total	10,741,536	9,787,669
Consumer lending | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	2,503	2,491
Total	147,659	163,259
Consumer lending | Current Accruing Loans
Nonaccrual and Past Due Loans
Total	10,837,491	9,901,147
Consumer lending | Current Accruing Loans | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	8,834,580	8,156,645
Consumer lending | Current Accruing Loans | HELOCs
Nonaccrual and Past Due Loans
Total	1,858,040	1,583,968
Consumer lending | Current Accruing Loans | Total residential mortgage
Nonaccrual and Past Due Loans
Total	10,692,620	9,740,613
Consumer lending | Current Accruing Loans | Other consumer
Nonaccrual and Past Due Loans
Total	144,871	160,534
Consumer lending | Total Accruing Past Due Loans
Nonaccrual and Past Due Loans
Total	18,712	18,780
Consumer lending | Total Accruing Past Due Loans | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	14,622	12,494
Consumer lending | Total Accruing Past Due Loans | HELOCs
Nonaccrual and Past Due Loans
Total	3,805	6,052
Consumer lending | Total Accruing Past Due Loans | Total residential mortgage
Nonaccrual and Past Due Loans
Total	18,427	18,546
Consumer lending | Total Accruing Past Due Loans | Other consumer
Nonaccrual and Past Due Loans
Total	285	234
Consumer lending | Accruing Loans 30-59  Days Past Due
Nonaccrual and Past Due Loans
Total	15,877	13,050
Consumer lending | Accruing Loans 30-59  Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	12,969	9,911
Consumer lending | Accruing Loans 30-59  Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total	2,643	2,922
Consumer lending | Accruing Loans 30-59  Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total	15,612	12,833
Consumer lending | Accruing Loans 30-59  Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total	265	217
Consumer lending | Accruing Loans 60-89  Days Past Due
Nonaccrual and Past Due Loans
Total	2,835	5,730
Consumer lending | Accruing Loans 60-89  Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total	1,653	2,583
Consumer lending | Accruing Loans 60-89  Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total	1,162	3,130
Consumer lending | Accruing Loans 60-89  Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total	2,815	5,713
Consumer lending | Accruing Loans 60-89  Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total	$ 20	$ 17