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, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Impaired loans	$ 33,775	$ 32,523
Allowance	3,646	3,058
Unpaid principal balance in total impaired loans	48,420	47,946
Non Accrual Loans
Impaired loans	14,732	12,505
Restructuring | Accrual Loans
Impaired loans	7,411	9,459
Restructuring | Non Accrual Loans
Impaired loans	11,632	10,559
Commercial
Impaired loans	5,041	5,608
Allowance	1,311	849
Unpaid principal balance in total impaired loans	6,765	7,943
Commercial | Non Accrual Loans
Impaired loans	1,893	1,906
Commercial | Restructuring | Accrual Loans
Impaired loans	1,769	2,207
Commercial | Restructuring | Non Accrual Loans
Impaired loans	1,379	1,495
All Other
Impaired loans	7,993	8,022
Allowance	604	626
Unpaid principal balance in total impaired loans	8,368	8,650
All Other | Non Accrual Loans
Impaired loans	1,753	0
All Other | Restructuring | Accrual Loans
Impaired loans	3,468	5,226
All Other | Restructuring | Non Accrual Loans
Impaired loans	2,772	2,796
Impaired Financing Receivables with Related Allowance
Impaired loans	12,327	12,217
Impaired Financing Receivables with Related Allowance | Non Accrual Loans
Impaired loans	5,950	4,505
Impaired Financing Receivables with Related Allowance | Restructuring | Accrual Loans
Impaired loans	2,077	4,329
Impaired Financing Receivables with Related Allowance | Restructuring | Non Accrual Loans
Impaired loans	4,300	3,383
Impaired Financing Receivables with Related Allowance | Commercial
Impaired loans	2,023	1,513
Impaired Financing Receivables with Related Allowance | Commercial | Non Accrual Loans
Impaired loans	1,080	374
Impaired Financing Receivables with Related Allowance | Commercial | Restructuring | Accrual Loans
Impaired loans	683	790
Impaired Financing Receivables with Related Allowance | Commercial | Restructuring | Non Accrual Loans
Impaired loans	260	349
Impaired Financing Receivables with Related Allowance | All Other
Impaired loans	2,982	3,003
Impaired Financing Receivables with Related Allowance | All Other | Non Accrual Loans
Impaired loans	960	0
Impaired Financing Receivables with Related Allowance | All Other | Restructuring | Accrual Loans
Impaired loans	1,394	2,365
Impaired Financing Receivables with Related Allowance | All Other | Restructuring | Non Accrual Loans
Impaired loans	628	638
Impaired Financing Receivables with No Related Allowance
Impaired loans	21,448	20,306
Impaired Financing Receivables with No Related Allowance | Non Accrual Loans
Impaired loans	8,782	8,000
Impaired Financing Receivables with No Related Allowance | Restructuring | Accrual Loans
Impaired loans	5,334	5,130
Impaired Financing Receivables with No Related Allowance | Restructuring | Non Accrual Loans
Impaired loans	7,332	7,176
Impaired Financing Receivables with No Related Allowance | Commercial
Impaired loans	3,018	4,095
Impaired Financing Receivables with No Related Allowance | Commercial | Non Accrual Loans
Impaired loans	813	1,532
Impaired Financing Receivables with No Related Allowance | Commercial | Restructuring | Accrual Loans
Impaired loans	1,086	1,417
Impaired Financing Receivables with No Related Allowance | Commercial | Restructuring | Non Accrual Loans
Impaired loans	1,119	1,146
Impaired Financing Receivables with No Related Allowance | All Other
Impaired loans	5,011	5,019
Impaired Financing Receivables with No Related Allowance | All Other | Non Accrual Loans
Impaired loans	793	0
Impaired Financing Receivables with No Related Allowance | All Other | Restructuring | Accrual Loans
Impaired loans	2,074	2,861
Impaired Financing Receivables with No Related Allowance | All Other | Restructuring | Non Accrual Loans
Impaired loans	2,144	2,158
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Impaired loans	4,133	4,128
Allowance	1,167	1,031
Unpaid principal balance in total impaired loans	10,357	10,318
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Non Accrual Loans
Impaired loans	1,477	1,742
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Restructuring | Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Restructuring | Non Accrual Loans
Impaired loans	2,656	2,386
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Impaired loans	9,458	7,654
Allowance	152	126
Unpaid principal balance in total impaired loans	14,171	12,351
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Non Accrual Loans
Impaired loans	6,674	6,189
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Restructuring | Accrual Loans
Impaired loans	2,174	852
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Restructuring | Non Accrual Loans
Impaired loans	610	613
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Impaired loans	7,150	7,111
Allowance	412	426
Unpaid principal balance in total impaired loans	8,759	8,684
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Non Accrual Loans
Impaired loans	2,935	2,668
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Restructuring | Accrual Loans
Impaired loans	0	1,174
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Restructuring | Non Accrual Loans
Impaired loans	4,215	3,269
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Acquisition, Development and Construction
Impaired loans	2,640	2,482
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Acquisition, Development and Construction | Non Accrual Loans
Impaired loans	1,477	1,360
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Acquisition, Development and Construction | Restructuring | Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Acquisition, Development and Construction | Restructuring | Non Accrual Loans
Impaired loans	1,163	1,122
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Investor Real Estate
Impaired loans	411	749
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Investor Real Estate | Non Accrual Loans
Impaired loans	411	749
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Investor Real Estate | Restructuring | Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Investor Real Estate | Restructuring | Non Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Owner Occupied Real Estate
Impaired loans	4,271	4,470
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Owner Occupied Real Estate | Non Accrual Loans
Impaired loans	2,022	2,022
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Owner Occupied Real Estate | Restructuring | Accrual Loans
Impaired loans	0	1,174
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with Related Allowance | Commercial Owner Occupied Real Estate | Restructuring | Non Accrual Loans
Impaired loans	2,249	1,274
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Acquisition, Development and Construction
Impaired loans	1,493	1,646
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Acquisition, Development and Construction | Non Accrual Loans
Impaired loans	0	382
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Acquisition, Development and Construction | Restructuring | Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Acquisition, Development and Construction | Restructuring | Non Accrual Loans
Impaired loans	1,493	1,264
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Investor Real Estate
Impaired loans	9,047	6,905
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Investor Real Estate | Non Accrual Loans
Impaired loans	6,263	5,440
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Investor Real Estate | Restructuring | Accrual Loans
Impaired loans	2,174	852
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Investor Real Estate | Restructuring | Non Accrual Loans
Impaired loans	610	613
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Owner Occupied Real Estate
Impaired loans	2,879	2,641
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Owner Occupied Real Estate | Non Accrual Loans
Impaired loans	913	646
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Owner Occupied Real Estate | Restructuring | Accrual Loans
Impaired loans	0	0
Commercial Real Estate Portfolio Segment | Impaired Financing Receivables with No Related Allowance | Commercial Owner Occupied Real Estate | Restructuring | Non Accrual Loans
Impaired loans	$ 1,966	$ 1,995