Loans - Pre-Modification and Post-Modification Outstanding Recorded Investments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	20	27	52	46
Pre-Modification Outstanding Recorded Investment	$ 27,611	$ 59,438	$ 38,983	$ 65,984
Post-Modification Outstanding Recorded Investment	27,459	57,283	36,882	62,139
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	6	8	10	13
Pre-Modification Outstanding Recorded Investment	13,912	18,278	16,750	19,700
Post-Modification Outstanding Recorded Investment	13,881	16,623	15,232	17,574
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	4	8	9	14
Pre-Modification Outstanding Recorded Investment	7,275	33,677	11,729	35,726
Post-Modification Outstanding Recorded Investment	7,266	33,487	11,727	35,453
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	4	2	5	4
Pre-Modification Outstanding Recorded Investment	4,936	4,557	5,474	6,711
Post-Modification Outstanding Recorded Investment	4,979	4,254	5,510	5,278
Commercial real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	8	10	14	18
Pre-Modification Outstanding Recorded Investment	12,211	38,234	17,203	42,437
Post-Modification Outstanding Recorded Investment	12,245	37,741	17,237	40,731
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	5	9	22	13
Pre-Modification Outstanding Recorded Investment	1,414	2,926	4,578	3,778
Post-Modification Outstanding Recorded Investment	1,259	2,919	4,016	3,767
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	1	0	6	2
Pre-Modification Outstanding Recorded Investment	74	0	452	69
Post-Modification Outstanding Recorded Investment	$ 74		$ 397	$ 67