Loans and the Allowance for Credit Losses - Loans Identified as TDRs (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract	21	24
Pre-Modification Outstanding Recorded Investment	$ 445	$ 1,801
Post-Modification Outstanding Recorded Investment	$ 400	$ 1,251
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract		3
Pre-Modification Outstanding Recorded Investment		$ 128
Post-Modification Outstanding Recorded Investment		$ 115
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract		5
Pre-Modification Outstanding Recorded Investment		$ 1,084
Post-Modification Outstanding Recorded Investment		$ 603
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract	2	1
Pre-Modification Outstanding Recorded Investment	$ 125	$ 57
Post-Modification Outstanding Recorded Investment	$ 120	$ 43
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract		8
Pre-Modification Outstanding Recorded Investment		$ 1,212
Post-Modification Outstanding Recorded Investment		$ 718
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract	4	7
Pre-Modification Outstanding Recorded Investment	$ 178	$ 456
Post-Modification Outstanding Recorded Investment	$ 166	$ 426
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract	14	7
Pre-Modification Outstanding Recorded Investment	$ 98	$ 69
Post-Modification Outstanding Recorded Investment	$ 74	$ 58
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications \| Contract	1	1
Pre-Modification Outstanding Recorded Investment	$ 44	$ 7
Post-Modification Outstanding Recorded Investment	$ 40	$ 6

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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