Credit Quality Assessment (Recorded Investment with Respect to Impaired loans, Associated Allowance by Applicable Portfolio Segment and Principal Balance of Impaired Loans prior to Amounts Charged-off) (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	$ 9,661	$ 11,411
Impaired loans without a specific allowance	19,033	18,008
Impaired loans	28,694	29,419
Impaired Financing Receivable, Related Allowance	2,886	2,894
Unpaid principal balance in total impaired loans	41,337	42,185
Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	7,866	9,104
Impaired loans without a specific allowance	10,160	8,676
Impaired loans	18,026	17,780
Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	881	687
Impaired loans without a specific allowance	4,739	4,810
Impaired loans	5,620	5,497
Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	914	1,620
Impaired loans without a specific allowance	4,134	4,522
Impaired loans	5,048	6,142
Commercial
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	1,743	1,468
Impaired loans without a specific allowance	2,438	2,426
Impaired loans	4,181	3,894
Impaired Financing Receivable, Related Allowance	1,047	788
Unpaid principal balance in total impaired loans	5,646	5,360
Commercial | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	659	473
Impaired loans without a specific allowance	1,013	1,115
Impaired loans	1,672	1,588
Commercial | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	881	687
Impaired loans without a specific allowance	15	23
Impaired loans	896	710
Commercial | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	203	308
Impaired loans without a specific allowance	1,410	1,288
Impaired loans	1,613	1,596
All Other
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	3,770	3,841
Impaired loans	3,770	3,841
Impaired Financing Receivable, Related Allowance	0	0
Unpaid principal balance in total impaired loans	4,086	4,126
All Other | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	0	0
Impaired loans	0	0
All Other | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	2,621	2,664
Impaired loans	2,621	2,664
All Other | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	1,149	1,177
Impaired loans	1,149	1,177
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	57	1,330
Impaired loans without a specific allowance	137	1,134
Impaired loans	194	2,464
Impaired Financing Receivable, Related Allowance	58	741
Unpaid principal balance in total impaired loans	4,456	7,044
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	57	1,330
Impaired loans without a specific allowance	0	0
Impaired loans	57	1,330
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	0	0
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	137	1,134
Impaired loans	137	1,134
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	2,661	2,364
Impaired loans without a specific allowance	9,465	7,915
Impaired loans	12,126	10,279
Impaired Financing Receivable, Related Allowance	715	541
Unpaid principal balance in total impaired loans	16,878	14,926
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	2,589	2,288
Impaired loans without a specific allowance	7,362	5,792
Impaired loans	9,951	8,080
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	2,103	2,123
Impaired loans	2,103	2,123
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	72	76
Impaired loans without a specific allowance	0	0
Impaired loans	72	76
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	5,200	6,249
Impaired loans without a specific allowance	3,223	2,692
Impaired loans	8,423	8,941
Impaired Financing Receivable, Related Allowance	1,066	824
Unpaid principal balance in total impaired loans	10,271	10,729
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	4,561	5,013
Impaired loans without a specific allowance	1,785	1,769
Impaired loans	6,346	6,782
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	0	0
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	639	1,236
Impaired loans without a specific allowance	1,438	923
Impaired loans	$ 2,077	$ 2,159