Credit Quality Assessment (Credit Quality of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	$ 14,026	$ 13,642
Non-accrual loans and leases	30,495	28,530
Current loans	3,366,347	3,082,209
Total loans and leases	3,412,439	3,127,392
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	1,571	3,011
Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	480	1,754
Non-accrual loans and leases	3,881	3,184
Current loans	418,926	384,605
Total loans and leases	423,855	390,781
Commercial | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	568	1,238
Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1	11
Non-accrual loans and leases	0	0
Current loans	18	43
Total loans and leases	19	54
Leases | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
Consumer
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	2,366	976
Non-accrual loans and leases	1,621	1,668
Current loans	440,742	422,908
Total loans and leases	444,729	425,552
Consumer | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	320
Non-accrual loans and leases	194	2,464
Current loans	238,966	202,340
Total loans and leases	239,160	205,124
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1,444	3,867
Non-accrual loans and leases	8,609	8,156
Current loans	700,641	628,170
Total loans and leases	710,694	640,193
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	855	2,814
Non-accrual loans and leases	7,932	8,941
Current loans	670,811	597,533
Total loans and leases	680,601	611,061
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	1,003	1,773
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	8,880	3,900
Non-accrual loans and leases	7,488	3,012
Current loans	757,521	710,974
Total loans and leases	773,889	717,886
Residential Real Estate Portfolio Segment | Residential Mortgage | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
Non-accrual loans and leases	770	1,105
Current loans	138,722	135,636
Total loans and leases	139,492	136,741
Residential Real Estate Portfolio Segment | Residential Construction | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	0	0
31-60 days
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	8,130	9,663
31-60 days | Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	55	759
31-60 days | Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	11
31-60 days | Consumer
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1,973	797
31-60 days | Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
31-60 days | Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	29	2,374
31-60 days | Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	401	2,658
31-60 days | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	5,672	3,064
31-60 days | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
61-90 days
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	5,895	3,979
61-90 days | Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	425	995
61-90 days | Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
61-90 days | Consumer
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	393	179
61-90 days | Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	320
61-90 days | Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1,415	1,493
61-90 days | Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	454	156
61-90 days | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	3,208	836
61-90 days | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1	0
> 90 days | Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1	0
> 90 days | Consumer
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	0
> 90 days | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	$ 0	$ 0