Credit Quality Assessment (Credit Quality of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	$ 9,628	$ 13,642
Non-accrual loans and leases	31,699	28,530
Current loans	3,245,287	3,082,209
Total loans and leases	3,288,865	3,127,392
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	2,251	3,011
Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	61	1,754
Non-accrual loans and leases	3,285	3,184
Current loans	405,251	384,605
Total loans and leases	409,795	390,781
Commercial | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans aquired with deteriorated credit quality	1,198	1,238
Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	2	11
Non-accrual loans and leases	0	0
Current loans	19	43
Total loans and leases	21	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	1,957	976
Non-accrual loans and leases	1,214	1,668
Current loans	433,294	422,908
Total loans and leases	436,465	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	222,909	202,340
Total loans and leases	223,103	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	1,525	3,867
Non-accrual loans and leases	10,023	8,156
Current loans	682,631	628,170
Total loans and leases	694,179	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	1,067	2,814
Non-accrual loans and leases	8,423	8,941
Current loans	633,430	597,533
Total loans and leases	643,973	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	1,053	1,773
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	5,016	3,900
Non-accrual loans and leases	7,780	3,012
Current loans	731,399	710,974
Total loans and leases	744,195	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	780	1,105
Current loans	136,354	135,636
Total loans and leases	137,134	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	5,834	9,663
31-60 days | Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	61	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	1,307	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	85	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	609	2,658
31-60 days | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	3,772	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	3,785	3,979
61-90 days | Commercial
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	0	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	643	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	1,440	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	458	156
61-90 days | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	1,244	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	9	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	2	0
> 90 days | Consumer
Financing Receivable Recorded Investment Past Due [Line Items]
Total past due	7	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