Business Combinations narrative (Details) (USD $)	0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended
	Nov. 01, 2014	Dec. 31, 2014	Apr. 02, 2013	Dec. 31, 2013	Dec. 31, 2012
Intermountain Community Bancorp [Member]
Business Acquisition [Line Items]
Business Combination, Purchase Price Allocation, Goodwill Amount	$ 38,585,000
Business Acquisition, Effective Date of Acquisition	Nov. 01, 2014
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	93,350,000
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets	10,900,000
business combinations, core deposit intangible percentage of core deposits	1.75%
Business Combination, Acquisition Related Costs		4,896,000
Business Combination, Purchase Price Allocation, Other Assets	35,353,000
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits	736,795,000
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
West Coast Bancorp [Member]
Business Acquisition [Line Items]
Business Combination, Purchase Price Allocation, Goodwill Amount			228,400,000
Business Acquisition, Effective Date of Acquisition			Apr. 01, 2013
Business Combination, Acquired Receivables, Fair Value			1,410,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net			312,400,000
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets			15,300,000
Business Combination, Acquisition Related Costs		4,536,000		25,488,000	1,780,000
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits			1,880,000,000
Business Combination, Cost of Acquired Entity, Purchase Price, Total			$ 540,800,000
Business Acquisition, Percentage of Voting Interests Acquired			100.00%