Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 location
Accounting Policies [Line Items]
Net investment in affordable housing program	$ 7,300,000
Tax credit from affordable housing program	1,500,000
Amortization method qualified affordable housing project investments, amortization	2,000,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results	1,100,000
Number Of Branch Locations	154
Number Of Days Used To Determine Treatment As Cash Equivalent	90 days
Number of Days of Delinqunecy at Which Loans Are Categorized As Non Accrual Status	90 days
Loans and Leases Receivable, Nonaccrual Loans Considered Impaired	500,000
Loans and Leases Receivable, Loans Evaluated For Impairment On Quarterly Basis, Outstanding	500,000
Correction of immaterial error, pre-tax increase to interest income on taxable securities	$ 2,600,000
Core Deposits [Member]
Accounting Policies [Line Items]
Estimated life of CDI, in years	10 years
WASHINGTON
Accounting Policies [Line Items]
Number Of Branch Locations	78
OREGON
Accounting Policies [Line Items]
Number Of Branch Locations	60
IDAHO
Accounting Policies [Line Items]
Number Of Branch Locations	16
Vehicles [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P5Y
Minimum [Member] | Building and Building Improvements [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P5Y
Minimum [Member] | Furniture and Fixtures [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P3Y
Minimum [Member] | Software [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P3Y
Maximum [Member] | Building and Building Improvements [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P39Y
Maximum [Member] | Furniture and Fixtures [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P7Y
Maximum [Member] | Software [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	P5Y