Business Combinations (Details) $ in Thousands		3 Months Ended
	Mar. 04, 2016 USD ($) location	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 82,594	$ 78,610
Bank Of America, Branch Locations
Business Acquisition [Line Items]
Number of businesses acquired | location	15
Premium on deposits, percentage	2.00%
Cash purchase price	$ 9,700
Cash and cash equivalents	456,611
Premises and equipment, net	3,113
Core deposit intangibles	6,427
Goodwill	3,984	4,000
Other assets	463
Total assets	470,598
Deposits	469,889
Other liabilities	709
Total liabilities and shareholders' equity	$ 470,598
Expenses related to branch acquisition		$ 2,300
Core Deposits
Business Acquisition [Line Items]
Useful life		10 years
Core Deposits | Bank Of America, Branch Locations
Business Acquisition [Line Items]
Useful life	9 years 12 months
Oregon | Bank Of America, Branch Locations
Business Acquisition [Line Items]
Number of businesses acquired | location	12
Washington | Bank Of America, Branch Locations
Business Acquisition [Line Items]
Number of businesses acquired | location	3