Credit Quality of Loan Portfolio by Segment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	$ 30,189	$ 47,548
Loans and leases 90 days past due	10	247
Restructured loans and leases	8,054	10,110
Total non-performing loans and leases	38,253	57,905
Other real estate owned	1,662	5,926
Total non-performing assets	39,915	63,831
Commercial
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	4,050	4,611
Loans and leases 90 days past due	0	24
Restructured loans and leases	2,512	4,373
Total non-performing loans and leases	6,562	9,008
Other real estate owned	408	1,829
Total non-performing assets	6,970	10,837
Leases
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	0	865
Loans and leases 90 days past due	0	0
Restructured loans and leases	0	0
Total non-performing loans and leases	0	865
Other real estate owned	0	0
Total non-performing assets	0	865
Consumer
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	2,004	2,410
Loans and leases 90 days past due	10	14
Restructured loans and leases	29	31
Total non-performing loans and leases	2,043	2,455
Other real estate owned	0	0
Total non-performing assets	2,043	2,455
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	5,086	6,332
Loans and leases 90 days past due	0	0
Restructured loans and leases	0	0
Total non-performing loans and leases	5,086	6,332
Other real estate owned	0	0
Total non-performing assets	5,086	6,332
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	6,877	11,843
Loans and leases 90 days past due	0	0
Restructured loans and leases	852	0
Total non-performing loans and leases	7,729	11,843
Other real estate owned	0	220
Total non-performing assets	7,729	12,063
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	4,202	13,681
Loans and leases 90 days past due	0	209
Restructured loans and leases	1,183	1,503
Total non-performing loans and leases	5,385	15,393
Other real estate owned	0	2,396
Total non-performing assets	5,385	17,789
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	5,643	4,681
Loans and leases 90 days past due	0	0
Restructured loans and leases	3,478	4,203
Total non-performing loans and leases	9,121	8,884
Other real estate owned	1,254	1,401
Total non-performing assets	10,375	10,285
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	2,327	3,125
Loans and leases 90 days past due	0	0
Restructured loans and leases	0	0
Total non-performing loans and leases	2,327	3,125
Other real estate owned	0	80
Total non-performing assets	$ 2,327	$ 3,205