Credit Quality of Loan Portfolio by Segment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	$ 47,548	$ 71,680
Loans and leases 90 days past due	247	577
Restructured loans and leases	10,110	6,881
Total non-performing loans and leases	57,905	79,138
Other real estate owned	5,926	4,431
Total non-performing assets	63,831	83,569
Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	4,611	7,226
Loans and leases 90 days past due	24	0
Restructured loans and leases	4,373	1,866
Total non-performing loans and leases	9,008	9,092
Other real estate owned	1,829	100
Total non-performing assets	10,837	9,192
Leases
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	865	853
Loans and leases 90 days past due	0	2
Restructured loans and leases	0	0
Total non-performing loans and leases	865	855
Other real estate owned	0	0
Total non-performing assets	865	855
Consumer Loan
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	2,410	1,786
Loans and leases 90 days past due	14	165
Restructured loans and leases	31	35
Total non-performing loans and leases	2,455	1,986
Other real estate owned	0	0
Total non-performing assets	2,455	1,986
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	6,332	18,702
Loans and leases 90 days past due	0	0
Restructured loans and leases	0	0
Total non-performing loans and leases	6,332	18,702
Other real estate owned	0	0
Total non-performing assets	6,332	18,702
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	11,843	16,963
Loans and leases 90 days past due	0	0
Restructured loans and leases	0	0
Total non-performing loans and leases	11,843	16,963
Other real estate owned	220	462
Total non-performing assets	12,063	17,425
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	13,681	14,709
Loans and leases 90 days past due	209	0
Restructured loans and leases	1,503	707
Total non-performing loans and leases	15,393	15,416
Other real estate owned	2,396	273
Total non-performing assets	17,789	15,689
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	4,681	5,722
Loans and leases 90 days past due	0	167
Restructured loans and leases	4,203	3,579
Total non-performing loans and leases	8,884	9,468
Other real estate owned	1,401	3,395
Total non-performing assets	10,285	12,863
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable, Recorded Investment [Line Items]
Non-accrual loans and leases	3,125	5,719
Loans and leases 90 days past due	0	243
Restructured loans and leases	0	694
Total non-performing loans and leases	3,125	6,656
Other real estate owned	80	201
Total non-performing assets	$ 3,205	$ 6,857