Loans Receivable and Allowance for Credit Losses (Aging Analysis on Loans Held-for-Investment) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	$ 99,607
Total Nonaccrual Loans	126,668
Current Accruing Loans	35,667,118
Total	35,893,393	$ 34,778,539
Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	78,342
Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	21,265
Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	61,858
Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	64,810
Commercial lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	26,247
Total Nonaccrual Loans	96,180
Current Accruing Loans	26,659,389
Total	26,781,816	25,914,252
Commercial lending | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	18,385
Total Nonaccrual Loans	89,079
Current Accruing Loans	12,483,300
Total	12,590,764	12,150,931
Commercial lending | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	6,986
Total Nonaccrual Loans	6,298
Current Accruing Loans	10,668,958
Total	10,682,242	10,278,448
Commercial lending | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	876
Total Nonaccrual Loans	803
Current Accruing Loans	2,900,922
Total	2,902,601	2,856,374
Commercial lending | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0
Total Nonaccrual Loans	0
Current Accruing Loans	606,209
Total	606,209	628,499
Commercial lending | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	7,862
Total Nonaccrual Loans	7,101
Current Accruing Loans	14,176,089
Total	14,191,052	13,763,321
Commercial lending | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	21,728
Commercial lending | Accruing Loans 30-59 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	15,168
Commercial lending | Accruing Loans 30-59 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	6,050
Commercial lending | Accruing Loans 30-59 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	510
Commercial lending | Accruing Loans 30-59 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0
Commercial lending | Accruing Loans 30-59 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	6,560
Commercial lending | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	4,519
Commercial lending | Accruing Loans 60-89 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	3,217
Commercial lending | Accruing Loans 60-89 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	936
Commercial lending | Accruing Loans 60-89 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	366
Commercial lending | Accruing Loans 60-89 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	0
Commercial lending | Accruing Loans 60-89 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	1,302
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	60,102
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	59,110
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	474
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	518
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0
Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	992
Commercial lending | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	36,078
Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	29,969
Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	5,824
Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	285
Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0
Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	6,109
Consumer lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	73,360
Total Nonaccrual Loans	30,488
Current Accruing Loans	9,007,729
Total	9,111,577	8,864,287
Consumer lending | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	58,663
Total Nonaccrual Loans	17,536
Current Accruing Loans	7,327,524
Total	7,403,723	7,108,590
Consumer lending | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	14,634
Total Nonaccrual Loans	10,446
Current Accruing Loans	1,427,782
Total	1,452,862	1,472,783
Consumer lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	73,297
Total Nonaccrual Loans	27,982
Current Accruing Loans	8,755,306
Total	8,856,585	8,581,373
Consumer lending | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	63
Total Nonaccrual Loans	2,506
Current Accruing Loans	252,423
Total	254,992	282,914
Consumer lending | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	56,614
Consumer lending | Accruing Loans 30-59 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	45,926
Consumer lending | Accruing Loans 30-59 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	10,654
Consumer lending | Accruing Loans 30-59 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	56,580
Consumer lending | Accruing Loans 30-59 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	34
Consumer lending | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	16,746
Consumer lending | Accruing Loans 60-89 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	12,737
Consumer lending | Accruing Loans 60-89 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	3,980
Consumer lending | Accruing Loans 60-89 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	16,717
Consumer lending | Accruing Loans 60-89 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans	29
Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,756
Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,312
Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	444
Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	1,756
Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	0
Consumer lending | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	28,732
Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	16,224
Consumer lending | Nonaccrual Loans 90 or More Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	10,002
Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	26,226
Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans	$ 2,506
Non-PCI Loans
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		101,283
Total Nonaccrual Loans		120,219
Current Accruing Loans		34,334,166
Total		34,555,668
Non-PCI Loans | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		73,871
Non-PCI Loans | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		27,412
Non-PCI Loans | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		35,570
Non-PCI Loans | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		84,649
Non-PCI Loans | Commercial lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		73,691
Total Nonaccrual Loans		92,095
Current Accruing Loans		25,611,253
Total		25,777,039
Non-PCI Loans | Commercial lending | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		48,155
Total Nonaccrual Loans		74,835
Current Accruing Loans		12,026,131
Total		12,149,121
Non-PCI Loans | Commercial lending | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		24,807
Total Nonaccrual Loans		16,441
Current Accruing Loans		10,123,999
Total		10,165,247
Non-PCI Loans | Commercial lending | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		729
Total Nonaccrual Loans		819
Current Accruing Loans		2,832,664
Total		2,834,212
Non-PCI Loans | Commercial lending | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		0
Total Nonaccrual Loans		0
Current Accruing Loans		628,459
Total		628,459
Non-PCI Loans | Commercial lending | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		25,536
Total Nonaccrual Loans		17,260
Current Accruing Loans		13,585,122
Total		13,627,918
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		54,149
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		31,121
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		22,830
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		198
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		0
Non-PCI Loans | Commercial lending | Accruing Loans 30-59 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		23,028
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		19,542
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		17,034
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		1,977
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		531
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		0
Non-PCI Loans | Commercial lending | Accruing Loans 60-89 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		2,508
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		32,158
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		31,084
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		540
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		534
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		0
Non-PCI Loans | Commercial lending | Nonaccrual Loans Less Than 90 Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		1,074
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		59,937
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Commercial and industrial (“C&I”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		43,751
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Commercial real estate (“CRE”)
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		15,901
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Real estate loan | Multifamily residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		285
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Construction and land
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		0
Non-PCI Loans | Commercial lending | Nonaccrual Loans 90 or More Days Past Due | Total CRE
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		16,186
Non-PCI Loans | Consumer lending
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		27,592
Total Nonaccrual Loans		28,124
Current Accruing Loans		8,722,913
Total		8,778,629
Non-PCI Loans | Consumer lending | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		20,517
Total Nonaccrual Loans		14,865
Current Accruing Loans		6,993,597
Total		7,028,979
Non-PCI Loans | Consumer lending | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		7,064
Total Nonaccrual Loans		10,742
Current Accruing Loans		1,448,930
Total		1,466,736
Non-PCI Loans | Consumer lending | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		27,581
Total Nonaccrual Loans		25,607
Current Accruing Loans		8,442,527
Total		8,495,715
Non-PCI Loans | Consumer lending | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		11
Total Nonaccrual Loans		2,517
Current Accruing Loans		280,386
Total		282,914
Non-PCI Loans | Consumer lending | Accruing Loans 30-59 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		19,722
Non-PCI Loans | Consumer lending | Accruing Loans 30-59 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		15,443
Non-PCI Loans | Consumer lending | Accruing Loans 30-59 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		4,273
Non-PCI Loans | Consumer lending | Accruing Loans 30-59 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		19,716
Non-PCI Loans | Consumer lending | Accruing Loans 30-59 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		6
Non-PCI Loans | Consumer lending | Accruing Loans 60-89 Days Past Due
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		7,870
Non-PCI Loans | Consumer lending | Accruing Loans 60-89 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		5,074
Non-PCI Loans | Consumer lending | Accruing Loans 60-89 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		2,791
Non-PCI Loans | Consumer lending | Accruing Loans 60-89 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		7,865
Non-PCI Loans | Consumer lending | Accruing Loans 60-89 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Accruing Past Due Loans		5
Non-PCI Loans | Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		3,412
Non-PCI Loans | Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		1,964
Non-PCI Loans | Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		1,448
Non-PCI Loans | Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		3,412
Non-PCI Loans | Consumer lending | Nonaccrual Loans Less Than 90 Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		0
Non-PCI Loans | Consumer lending | Nonaccrual Loans 90 or More Days Past Due
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		24,712
Non-PCI Loans | Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Real estate loan | Single-family residential
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		12,901
Non-PCI Loans | Consumer lending | Nonaccrual Loans 90 or More Days Past Due | HELOCs
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		9,294
Non-PCI Loans | Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Total residential mortgage
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		22,195
Non-PCI Loans | Consumer lending | Nonaccrual Loans 90 or More Days Past Due | Other consumer
Nonaccrual and Past Due Loans
Total Nonaccrual Loans		$ 2,517