Loans Receivable and Allowance for Credit Losses (Details 3) - Loans Receivable - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	$ 27,210,666	$ 25,503,139
CRE
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	9,125,849	8,690,863
CRE | Income producing
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	8,465,030	8,016,109
CRE | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	550,781	551,560
CRE | Land
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	110,038	123,194
C&I
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	10,187,349	9,640,563
C&I | Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	9,424,236	8,959,633
C&I | Trade finance
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	763,113	680,930
Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	5,774,229	5,095,718
Residential | Real estate loan | Single-family
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	4,001,488	3,509,779
Residential | Real estate loan | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,772,741	1,585,939
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	2,123,239	2,075,995
Non-PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	26,645,211	24,860,694
Non-PCI Loans | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	25,997,635	24,177,983
Non-PCI Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	237,685	212,927
Non-PCI Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	385,050	464,609
Non-PCI Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	24,841	5,167
Non-PCI Loans | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	8
Non-PCI Loans | CRE
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	8,801,059	8,340,497
Non-PCI Loans | CRE | Income producing
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	8,141,483	7,667,661
Non-PCI Loans | CRE | Income producing | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	8,003,443	7,476,804
Non-PCI Loans | CRE | Income producing | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	18,859	29,005
Non-PCI Loans | CRE | Income producing | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	119,181	161,852
Non-PCI Loans | CRE | Income producing | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | CRE | Income producing | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | CRE | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	550,781	551,560
Non-PCI Loans | CRE | Construction | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	521,240	551,560
Non-PCI Loans | CRE | Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	20,548	0
Non-PCI Loans | CRE | Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	8,993	0
Non-PCI Loans | CRE | Construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | CRE | Construction | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | CRE | Land
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	108,795	121,276
Non-PCI Loans | CRE | Land | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	93,691	107,976
Non-PCI Loans | CRE | Land | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | CRE | Land | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	15,104	13,290
Non-PCI Loans | CRE | Land | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	10
Non-PCI Loans | CRE | Land | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | C&I
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	10,166,688	9,602,176
Non-PCI Loans | C&I | Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	9,403,575	8,921,246
Non-PCI Loans | C&I | Commercial business | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	9,049,939	8,559,674
Non-PCI Loans | C&I | Commercial business | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	160,656	155,276
Non-PCI Loans | C&I | Commercial business | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	168,139	201,139
Non-PCI Loans | C&I | Commercial business | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	24,841	5,157
Non-PCI Loans | C&I | Commercial business | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | C&I | Trade finance
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	763,113	680,930
Non-PCI Loans | C&I | Trade finance | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	728,700	635,027
Non-PCI Loans | C&I | Trade finance | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	21,176	9,435
Non-PCI Loans | C&I | Trade finance | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	13,237	36,460
Non-PCI Loans | C&I | Trade finance | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | C&I | Trade finance | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	8
Non-PCI Loans | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	5,570,781	4,860,954
Non-PCI Loans | Residential | Real estate loan | Single-family
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	3,873,803	3,370,669
Non-PCI Loans | Residential | Real estate loan | Single-family | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	3,838,847	3,341,015
Non-PCI Loans | Residential | Real estate loan | Single-family | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	10,216	10,179
Non-PCI Loans | Residential | Real estate loan | Single-family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	24,740	19,475
Non-PCI Loans | Residential | Real estate loan | Single-family | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | Residential | Real estate loan | Single-family | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | Residential | Real estate loan | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,696,978	1,490,285
Non-PCI Loans | Residential | Real estate loan | Multifamily | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,676,251	1,462,522
Non-PCI Loans | Residential | Real estate loan | Multifamily | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	2,268
Non-PCI Loans | Residential | Real estate loan | Multifamily | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	20,727	25,495
Non-PCI Loans | Residential | Real estate loan | Multifamily | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | Residential | Real estate loan | Multifamily | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	2,106,683	2,057,067
Non-PCI Loans | Consumer | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	2,085,524	2,043,405
Non-PCI Loans | Consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	6,230	6,764
Non-PCI Loans | Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	14,929	6,898
Non-PCI Loans | Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
Non-PCI Loans | Consumer | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	565,455	642,445
PCI Loans | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	499,962	568,844
PCI Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	2,932	5,566
PCI Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	62,561	68,035
PCI Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	324,790	350,366
PCI Loans | CRE | Income producing
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	323,547	348,448
PCI Loans | CRE | Income producing | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	272,926	293,529
PCI Loans | CRE | Income producing | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	472	3,239
PCI Loans | CRE | Income producing | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	50,149	51,680
PCI Loans | CRE | Income producing | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE | Income producing | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE | Land
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,243	1,918
PCI Loans | CRE | Land | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	914	1,562
PCI Loans | CRE | Land | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE | Land | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	329	356
PCI Loans | CRE | Land | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | CRE | Land | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | C&I
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	20,661	38,387
PCI Loans | C&I | Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	20,661	38,387
PCI Loans | C&I | Commercial business | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	17,312	33,885
PCI Loans | C&I | Commercial business | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	585	772
PCI Loans | C&I | Commercial business | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	2,764	3,730
PCI Loans | C&I | Commercial business | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | C&I | Commercial business | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | C&I | Trade finance
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	203,448	234,764
PCI Loans | Residential | Real estate loan | Single-family
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	127,685	139,110
PCI Loans | Residential | Real estate loan | Single-family | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	124,216	136,245
PCI Loans | Residential | Real estate loan | Single-family | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,506	1,239
PCI Loans | Residential | Real estate loan | Single-family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,963	1,626
PCI Loans | Residential | Real estate loan | Single-family | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Residential | Real estate loan | Single-family | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Residential | Real estate loan | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	75,763	95,654
PCI Loans | Residential | Real estate loan | Multifamily | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	69,657	86,190
PCI Loans | Residential | Real estate loan | Multifamily | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Residential | Real estate loan | Multifamily | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	6,106	9,464
PCI Loans | Residential | Real estate loan | Multifamily | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Residential | Real estate loan | Multifamily | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	16,556	18,928
PCI Loans | Consumer | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	14,937	17,433
PCI Loans | Consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	369	316
PCI Loans | Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	1,250	1,179
PCI Loans | Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	0	0
PCI Loans | Consumer | Loss
Financing Receivable, Recorded Investment [Line Items]
Total loans held-for-investment	$ 0	$ 0