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Derivatives - Additional Information (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 USD ($) Derivatives | Sep. 30, 2016 USD ($) | Sep. 30, 2017 USD ($) Derivatives | Sep. 30, 2016 USD ($) | Dec. 31, 2016 USD ($)
Risk participation Agreements [Line Items] |  |  |  |  |
HedgedItemsOfCashFlowHedge | $ 150,000 |  | $ 150,000 |  |
Derivative Instruments Designated As Hedging Instruments Interest Income |  | $ 404 |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | $ 9 | 16 |  |  |
Risk Participation Agreements Purchased [Domain] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Number of interest rate swaps | Derivatives | 32 |  | 32 |  |
Risk Participation Agreements Sold [Domain] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Number of interest rate swaps | Derivatives | 8 |  | 8 |  |
Forward Contracts [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | $ 61 | 0 | $ (34) | $ 0 |
Derivative Liability, Cost Basis, Gross Asset | 13,800 |  | 13,800 |  |
Derivative Liability, Fair Value, Gross Asset | 14,300 |  | 14,300 |  |
Derivative Liability, Notional Amount, Gross Asset | 23,300 |  | 23,300 |  |
Forward Contracts [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 34 |  | 34 |  | $ 0
Derivative, Notional Amount | 28,000 |  | 28,000 |  | 0
Foreign Exchange [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | 2 | $ 7 | 3 | 14 |
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | (4) |  | (4) |  | 8
Derivative, Notional Amount | 7,785 |  | 7,785 |  | 4,749
Derivative Liability, Cost Basis, Gross Asset | 7,800 |  | 7,800 |  | 4,700
Derivative Liability, Fair Value, Gross Asset | 7,800 |  | 7,800 |  | 4,700
Three Year Maturity [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Notional Amount | 35,000 |  | 35,000 |  |
Four Year Maturity [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Notional Amount | 115,000 |  | 115,000 |  |
Interest Rate Swap [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative Instruments Designated As Hedging Instruments Interest Income | 35 |  | 420 | 1,258 |
Derivative, Net Hedge Ineffectiveness Gain (Loss) |  |  | 82 | $ 57 |
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] |  |  |  |  |
Risk participation Agreements [Line Items] |  |  |  |  |
Derivative, Fair Value, Net | 189 |  | 189 |  | 443
Derivative, Notional Amount | $ 150,000 |  | $ 150,000 |  | $ 200,000

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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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