Credit Quality Assessment (Impaired Loans by Portfolio) (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	$ 30,055	$ 34,331
Contractual interest income due on impaired loans during the period	2,016	2,339
Interest income on impaired loans recognized on a cash basis	745	773
Interest income on impaired loans recognized on an accrual basis	239	280
Commercial
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	4,574	5,308
Contractual interest income due on impaired loans during the period	353	311
Interest income on impaired loans recognized on a cash basis	197	252
Interest income on impaired loans recognized on an accrual basis	73	63
All Other
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	4,477	7,082
Contractual interest income due on impaired loans during the period	204	87
Interest income on impaired loans recognized on a cash basis	122	60
Interest income on impaired loans recognized on an accrual basis	76	106
Commercial Real Estate Portfolio Segment \| Commercial Acquisition, Development and Construction
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	1,054	3,651
Contractual interest income due on impaired loans during the period	231	352
Interest income on impaired loans recognized on a cash basis	11	39
Interest income on impaired loans recognized on an accrual basis	0	0
Commercial Real Estate Portfolio Segment \| Commercial Investor Real Estate
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	11,322	9,327
Contractual interest income due on impaired loans during the period	685	730
Interest income on impaired loans recognized on a cash basis	132	78
Interest income on impaired loans recognized on an accrual basis	81	111
Commercial Real Estate Portfolio Segment \| Commercial Owner Occupied Real Estate
Financing Receivable Impaired [Line Items]
Average impaired loans for the period	8,628	8,963
Contractual interest income due on impaired loans during the period	543	859
Interest income on impaired loans recognized on a cash basis	283	344
Interest income on impaired loans recognized on an accrual basis	$ 9	$ 0

Loans and Leases Receivable, Impaired, Contractual Interest Income

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- Definition

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+ References

No definition available.

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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+ References

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