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	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	$ 9,654	$ 11,411
Impaired loans without a specific allowance	21,251	18,008
Impaired loans	30,905	29,419
Impaired Financing Receivable, Related Allowance	3,002	2,894
Unpaid principal balance in total impaired loans	44,554	42,185
Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	7,925	9,104
Impaired loans without a specific allowance	11,445	8,676
Impaired loans	19,370	17,780
Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	863	687
Impaired loans without a specific allowance	5,556	4,810
Impaired loans	6,419	5,497
Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	866	1,620
Impaired loans without a specific allowance	4,250	4,522
Impaired loans	5,116	6,142
Commercial
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	2,165	1,468
Impaired loans without a specific allowance	3,195	2,426
Impaired loans	5,360	3,894
Impaired Financing Receivable, Related Allowance	1,278	788
Unpaid principal balance in total impaired loans	7,483	5,360
Commercial | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	1,140	473
Impaired loans without a specific allowance	999	1,115
Impaired loans	2,139	1,588
Commercial | Restructuring | Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	863	687
Impaired loans without a specific allowance	616	23
Impaired loans	1,479	710
Commercial | Restructuring | Non Accrual Loans
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	162	308
Impaired loans without a specific allowance	1,580	1,288
Impaired loans	1,742	1,596
All Other
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	0	0
Impaired loans without a specific allowance	6,482	3,841
Impaired loans	6,482	3,841
Impaired Financing Receivable, Related Allowance	0	0
Unpaid principal balance in total impaired loans	7,184	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	2,750	0
Impaired loans	2,750	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	2,612	2,664
Impaired loans	2,612	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	1,120	1,177
Impaired loans	1,120	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	57	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	2,654	2,364
Impaired loans without a specific allowance	8,043	7,915
Impaired loans	10,697	10,279
Impaired Financing Receivable, Related Allowance	709	541
Unpaid principal balance in total impaired loans	15,355	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	5,955	5,792
Impaired loans	8,544	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	2,088	2,123
Impaired loans	2,088	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	65	76
Impaired loans without a specific allowance	0	0
Impaired loans	65	76
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Impaired [Line Items]
Impaired loans with a specific allowance	4,778	6,249
Impaired loans without a specific allowance	3,394	2,692
Impaired loans	8,172	8,941
Impaired Financing Receivable, Related Allowance	958	824
Unpaid principal balance in total impaired loans	10,076	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	4,139	5,013
Impaired loans without a specific allowance	1,741	1,769
Impaired loans	5,880	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	240	0
Impaired loans	240	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	1,413	923
Impaired loans	$ 2,052	$ 2,159