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Derivatives - Additional Information (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 USD ($) Derivatives | Sep. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) Derivatives | Sep. 30, 2017 USD ($) | Dec. 31, 2017 USD ($)
Risk participation Agreements [Line Items] |  |  |  |  |
HedgedItemsOfCashFlowHedge | $ 65,000 |  | $ 65,000 |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | $ 221 | $ 0 |  |  |
Risk Participation Agreements Purchased [Domain] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Number of interest rate swaps | Derivatives | 50 |  | 50 |  |
Risk Participation Agreements Sold [Domain] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Number of interest rate swaps | Derivatives | 12 |  | 12 |  |
Forward Contracts [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | $ 125 | 61 | $ 96 | $ (34) |
Derivative Liability, Cost Basis, Gross Asset | 7,600 |  | 7,600 |  | $ 14,300
Derivative Liability, Fair Value, Gross Asset | 8,200 |  | 8,200 |  | 14,700
Derivative Liability, Notional Amount, Gross Asset | 16,700 |  | 16,700 |  | 13,800
Forward Contracts [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 77 |  | 77 |  | (19)
Derivative, Notional Amount | 19,000 |  | 19,000 |  | 17,000
Interest Rate Contract [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) |  |  | (432) | 0 |
Foreign Exchange [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | 2 | 2 | 10 | 3 |
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | (6) |  | (6) |  | 70
Derivative, Notional Amount | 4,058 |  | 4,058 |  | 10,077
Derivative Liability, Cost Basis, Gross Asset | 4,000 |  | 4,000 |  | 10,000
Derivative Liability, Fair Value, Gross Asset | 4,000 |  | 4,000 |  | 10,100
Interest Rate Swap [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative Instruments Designated As Hedging Instruments Interest Income | (193) | 35 | (424) | 420 |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | 0 | $ 9 | 10 | $ 82 |
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 294 |  | 294 |  | (459)
Derivative, Notional Amount | $ 65,000 |  | $ 65,000 |  | $ 150,000

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- Definition HedgedItemsOfCashFlowHedge + References No definition available. + Details
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- Definition [Line Items] for Risk participation Agreements [Table] + References No definition available. + Details
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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611 + Details
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- Definition Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959 + Details
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