Business Combinations narrative (Details) - USD ($) $ in Thousands			12 Months Ended
	Nov. 01, 2014	Apr. 02, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intermountain Community Bancorp [Member]
Business Acquisition [Line Items]
Business combinations, provisional information, initial accounting incomplete, adjustment, goodwill	$ 225
Business Combination, Purchase Price Allocation, Goodwill Amount	$ 38,810
Business Acquisition, Effective Date of Acquisition	Nov. 01, 2014
Business Combination, Cost of Acquired Entity, Purchase Price, Total	$ 131,935
Business combinations, provisional information, initial accounting incomplete, adjustment, other assets	225
Business Combination, Acquired Receivables, Fair Value	502,595
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	93,125
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets	$ 10,900
business combinations, core deposit intangible percentage of core deposits	1.75%
Business Combination, Acquisition Related Costs			$ 10,845	$ 4,896
Business Combination, Purchase Price Allocation, Other Assets	$ 35,128
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits	$ 736,795
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
West Coast Bancorp [Member]
Business Acquisition [Line Items]
Business Combination, Purchase Price Allocation, Goodwill Amount		$ 228,398
Business Acquisition, Effective Date of Acquisition		Apr. 01, 2013
Business Combination, Cost of Acquired Entity, Purchase Price, Total		$ 540,791
Business Combination, Acquired Receivables, Fair Value		1,407,798
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		312,393
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets		$ 15,257
business combinations, core deposit intangible percentage of core deposits		0.89%
Business Combination, Acquisition Related Costs			$ 72	$ 4,536	$ 25,488
Business Combination, Purchase Price Allocation, Other Assets		$ 75,820
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits		$ 1,883,407
Business Acquisition, Percentage of Voting Interests Acquired		100.00%