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Business combinations (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Nov. 01, 2014 | Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014
Business Acquisition [Line Items] |  |  |  |  |
Business combinations, provisional information, initial accounting incomplete, adjustment, other assets | $ 225 |  |  |  |
Business combinations, provisional information, initial accounting incomplete, adjustment, goodwill | $ 225 |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired | 100.00% |  |  |  |
Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Acquisition, Effective Date of Acquisition | Nov. 01, 2014 |  |  |  |
Business Acquisition, Cost of Acquired Entity, Purchase Price | $ 131,935 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents | 47,283 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities | 299,458 |  |  |  |
Business Combination, Purchase Price Allocation, FHLB Stock | 2,124 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net | 93,125 |  |  |  |
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits | (736,795) |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt | (22,904) |  |  |  |
Business combination, purchase price allocation, securities sold under agreements to repurchase | (59,043) |  |  |  |
Business Combination, Purchase Price Allocation, Other Liabilities | (13,725) |  |  |  |
Business Combination, Acquired Receivables, Fair Value | 502,595 |  |  |  |
Business Combination, Purchase Price Allocation, Accrued Interest Receivable | 4,656 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment | 20,696 |  |  |  |
Business Combination, Purchase Price Allocation, Other Real Estate Owned | 2,752 |  |  |  |
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets | 10,900 |  |  |  |
Business Combination, Purchase Price Allocation, Other Assets | 35,128 |  |  |  |
Business Acquisition, Purchase Price Allocation, Goodwill Amount | $ 38,810 |  |  |  |
Business Acquisition, Pro Forma Revenue |  |  |  |  | $ 300,151
Business Acquisition, Pro Forma Net Income (Loss) |  |  |  |  | $ 66,788
Business Acquisition, Pro Forma Earnings Per Share, Basic |  |  |  |  | $ 1.19
Business Acquisition, Pro Forma Earnings Per Share, Diluted |  |  |  |  | $ 1.18
Business Combination, Acquisition Related Costs |  | $ 428 | $ 459 | $ 8,973 | $ 459
business combinations, core deposit intangible percentage of core deposits | 1.75% |  |  |  |
West Coast Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  |  | 2,800 | 72 | 4,400
Compensation and employee benefits [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | 0 | 0 | 3,308 | 0
Occupancy [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | 181 | 0 | 1,484 | 0
Advertising and promotion [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | 40 | 27 | 383 | 27
Data processing and communications [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | 42 | 0 | 1,780 | 0
Legal and professional fees [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | 71 | 388 | 1,089 | 388
Other noninterest expenses [Member] | Intermountain Community Bancorp [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Business Combination, Acquisition Related Costs |  | $ 94 | $ 44 | $ 929 | $ 44

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- Definition business combinations, purchase price allocation, loans + References No definition available. + Details
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- Definition Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e845-128460 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Acquisition Date -URI http://asc.fasb.org/extlink&oid=6919109 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e848-128460 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460 + Details
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477 + Details
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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition The amount of property, plant, and equipment recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 + Details
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