Derivative Financial Instruments - Fair Values Instruments (Detail)	Dec. 31, 2017 USD ($)
Derivatives, Fair Value [Line Items]
Notional	$ 176,327,000
Fair Value	(2,491,000)
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional	75,000,000
Derivatives Designated as Hedging Instruments \| Other liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	(3,172,000)
Derivatives Designated as Hedging Instruments \| Interest Rate Products \| Other liabilities
Derivatives, Fair Value [Line Items]
Notional	75,000,000
Derivative liabilities, fair value	(3,172,000)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Notional	101,327,000
Fair Value	681,000
Derivatives not designated as hedging instruments \| Interest Rate Lock Commitment with Customers \| Other liabilities
Derivatives, Fair Value [Line Items]
Notional	8,992,000
Derivative liabilities, fair value	(23,000)
Derivatives not designated as hedging instruments \| Interest Rate Lock Commitment with Customers \| Other assets
Derivatives, Fair Value [Line Items]
Notional	44,079,000
Derivative assets, fair value	571,000
Derivatives not designated as hedging instruments \| Forward Sale Commitments \| Other liabilities
Derivatives, Fair Value [Line Items]
Notional	19,192,000
Derivative liabilities, fair value	(47,000)
Derivatives not designated as hedging instruments \| Forward Sale Commitments \| Other assets
Derivatives, Fair Value [Line Items]
Notional	29,064,000
Derivative assets, fair value	$ 180,000

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other 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. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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-Section 50
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313

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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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

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- Definition

Fair value, after the effects of master netting arrangements, of a 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. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313

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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.

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