Loans Receivable and Allowance for Credit Losses (Non-PCI TDR Modifications) (Details) - Non-PCI impaired loans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	$ 43,651	$ 65,762	$ 36,254
Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	19,164	57,729	17,191
Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	8,003	0	18,588
Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	6,722	0
Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	237	0
Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	16,484	1,074	475
Commercial Lending
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	43,496	64,112	35,975
Commercial Lending | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	19,164	57,132	16,912
Commercial Lending | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	7,848	0	18,588
Commercial Lending | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	5,876	0
Commercial Lending | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	30	0
Commercial Lending | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	16,484	1,074	475
Commercial Lending | C&I
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	37,900	40,405	34,165
Commercial Lending | C&I | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	13,568	34,499	16,364
Commercial Lending | C&I | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	7,848	0	17,801
Commercial Lending | C&I | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	5,876	0
Commercial Lending | C&I | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	30	0
Commercial Lending | C&I | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	16,484	0	0
Commercial Lending | CRE
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,627	18,824	1,727
Commercial Lending | CRE | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,627	17,750	548
Commercial Lending | CRE | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	0	787
Commercial Lending | CRE | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	0	0
Commercial Lending | CRE | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	0	0
Commercial Lending | CRE | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	1,074	392
Commercial Lending | Residential loan | Multifamily
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,969
Commercial Lending | Residential loan | Multifamily | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,969
Commercial Lending | Residential loan | Multifamily | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Commercial Lending | Residential loan | Multifamily | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Commercial Lending | Residential loan | Multifamily | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Commercial Lending | Residential loan | Multifamily | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Commercial Lending | Construction and land
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		4,883	83
Commercial Lending | Construction and land | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		4,883	0
Commercial Lending | Construction and land | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	0
Commercial Lending | Construction and land | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	0
Commercial Lending | Construction and land | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	0
Commercial Lending | Construction and land | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	83
Consumer Lending
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	155	1,650	279
Consumer Lending | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	597	279
Consumer Lending | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	155	0	0
Consumer Lending | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	846	0
Consumer Lending | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	207	0
Consumer Lending | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	0	0
Consumer Lending | Residential loan | Single-family
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		1,268	279
Consumer Lending | Residential loan | Single-family | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		264	279
Consumer Lending | Residential loan | Single-family | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	0
Consumer Lending | Residential loan | Single-family | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		797	0
Consumer Lending | Residential loan | Single-family | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		207	0
Consumer Lending | Residential loan | Single-family | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment		0	$ 0
Consumer Lending | HELOCs
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	155	382
Consumer Lending | HELOCs | Principal
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	333
Consumer Lending | HELOCs | Principal and Interest
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	155	0
Consumer Lending | HELOCs | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	49
Consumer Lending | HELOCs | Interest Deferments
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0	0
Consumer Lending | HELOCs | Other
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	$ 0	$ 0