Loans Receivable and Allowance for Credit Losses (Aging Analysis on Non-PCI Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Nonaccrual and Past Due Loans
Total loans	$ 34,778,539	$ 32,385,189
Commercial Lending
Nonaccrual and Past Due Loans
Total loans	25,914,252	24,326,631
Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total loans	12,150,931	12,056,970
Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total loans	10,278,448	9,260,199
Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total loans	2,856,374	2,470,668
Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total loans	628,499	538,794
Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total loans	13,763,321	12,269,661
Consumer Lending
Nonaccrual and Past Due Loans
Total loans	8,864,287	8,058,558
Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total loans	7,108,590	6,036,454
Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total loans	1,472,783	1,690,834
Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total loans	8,581,373	7,727,288
Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total loans	282,914	331,270
Non-PCI loans
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	101,283	79,230
Total Nonaccrual Loans	120,219	85,693
Current Accruing Loans	34,334,166	31,912,243
Total loans	34,555,668	32,077,166
Non-PCI loans | Commercial Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	73,691	52,323
Total Nonaccrual Loans	92,095	69,318
Current Accruing Loans	25,611,253	24,003,018
Total loans	25,777,039	24,124,659
Non-PCI loans | Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	48,155	40,202
Total Nonaccrual Loans	74,835	43,840
Current Accruing Loans	12,026,131	11,970,776
Total loans	12,149,121	12,054,818
Non-PCI loans | Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	24,807	7,740
Total Nonaccrual Loans	16,441	24,218
Current Accruing Loans	10,123,999	9,065,207
Total loans	10,165,247	9,097,165
Non-PCI loans | Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	729	4,174
Total Nonaccrual Loans	819	1,260
Current Accruing Loans	2,832,664	2,428,490
Total loans	2,834,212	2,433,924
Non-PCI loans | Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0	207
Total Nonaccrual Loans	0	0
Current Accruing Loans	628,459	538,545
Total loans	628,459	538,752
Non-PCI loans | Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	25,536	12,121
Total Nonaccrual Loans	17,260	25,478
Current Accruing Loans	13,585,122	12,032,242
Total loans	13,627,918	12,069,841
Non-PCI loans | Consumer Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	27,592	26,907
Total Nonaccrual Loans	28,124	16,375
Current Accruing Loans	8,722,913	7,909,225
Total loans	8,778,629	7,952,507
Non-PCI loans | Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	20,517	22,495
Total Nonaccrual Loans	14,865	5,259
Current Accruing Loans	6,993,597	5,911,504
Total loans	7,028,979	5,939,258
Non-PCI loans | Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	7,064	4,389
Total Nonaccrual Loans	10,742	8,614
Current Accruing Loans	1,448,930	1,668,976
Total loans	1,466,736	1,681,979
Non-PCI loans | Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	27,581	26,884
Total Nonaccrual Loans	25,607	13,873
Current Accruing Loans	8,442,527	7,580,480
Total loans	8,495,715	7,621,237
Non-PCI loans | Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	11	23
Total Nonaccrual Loans	2,517	2,502
Current Accruing Loans	280,386	328,745
Total loans	282,914	331,270
Non-PCI loans | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	73,871	50,382
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	54,149	33,153
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	31,121	21,032
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	22,830	7,740
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	198	4,174
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0	207
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	23,028	12,121
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Consumer Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	19,722	17,229
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	15,443	14,645
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	4,273	2,573
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	19,716	17,218
Non-PCI loans | Accruing Loans 30-59 Days Past Due | Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	6	11
Non-PCI loans | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	27,412	28,848
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	19,542	19,170
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	17,034	19,170
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	1,977	0
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	531	0
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0	0
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	2,508	0
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Consumer Lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	7,870	9,678
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	5,074	7,850
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	2,791	1,816
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	7,865	9,666
Non-PCI loans | Accruing Loans 60-89 Days Past Due | Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	5	12
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	35,570	23,800
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	32,158	21,868
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	31,084	17,097
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	540	3,704
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	534	1,067
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0	0
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,074	4,771
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Consumer Lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	3,412	1,932
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,964	509
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,448	1,423
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	3,412	1,932
Non-PCI loans | Nonaccrual Loans Less Than 90 Days Past Due | Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0	0
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	84,649	61,893
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	59,937	47,450
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending | C&I
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	43,751	26,743
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending | CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	15,901	20,514
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending | Residential loan | Multifamily
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	285	193
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0	0
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Commercial Lending | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	16,186	20,707
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Consumer Lending
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	24,712	14,443
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Consumer Lending | Residential loan | Single-family
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	12,901	4,750
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Consumer Lending | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	9,294	7,191
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Consumer Lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	22,195	11,941
Non-PCI loans | Nonaccrual Loans 90 or More Days Past Due | Consumer Lending | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	$ 2,517	$ 2,502