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Loans and Credit Quality - Narrative (Details) |  | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Apr. 01, 2014 USD ($) purchased_loan | Sep. 30, 2017 USD ($) contract financing_commitment | Dec. 31, 2016 USD ($) contract
Receivables [Abstract] |  |  |
Net nonaccrual loans |  | $ 22,494,000 | $ 12,480,000
Nonperforming loans minimum threshold for individual impairment evaluation |  | 50,000 |
Recorded investment in loans considered to be impaired |  | 39,722,000 | 38,656,000
Business Acquisition [Line Items] |  |  |
Total |  | $ 25,968,000 | $ 16,200,000
Number of commitments on TDR | financing_commitment |  | 0 |
Charge offs on loans later classified as TDRs |  | $ 731,000 |
TDR with specific impairment | contract |  | 4 | 4
TDR that subsequently defaulted | contract |  | 0 | 0
Alaska Pacific Bancshares |  |  |
Business Acquisition [Line Items] |  |  |
Purchased impaired loans | purchased_loan | 18 |  |
Accretable yield on purchased loans | $ 0 |  |
Fair value of purchased credit impaired loans | $ 3,900,000 | $ 942,000 |

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- Definition Financing Receivable, Recorded Investment, Nonaccrual Status, Excluding Government Guaranteed Payments + References No definition available. + Details
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- Definition Nonperforming loans minimum threshold for individual impairment evaluation. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 + Details
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- Definition Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
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