Credit Quality of Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	$ 18,342	$ 11,660
61-90 days	13,539	3,793
> 90 days	15	247
Total past due	31,896	15,700
Non-accrual loans and leases	37,966	47,548
Loans aquired with deteriorated credit quality	6,600	7,200
Current loans	2,528,996	2,460,680
Total loans and leases	2,605,458	2,531,128
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	4,241	2,138
61-90 days	471	212
> 90 days	15	24
Total past due	4,727	2,374
Non-accrual loans and leases	4,483	4,611
Loans aquired with deteriorated credit quality	1,686	1,978
Current loans	324,083	337,745
Total loans and leases	334,979	346,708
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	0	7
61-90 days	0	68
> 90 days	0	0
Total past due	0	75
Non-accrual loans and leases	0	865
Loans aquired with deteriorated credit quality	0	0
Current loans	1,415	2,481
Total loans and leases	1,415	3,421
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	523	496
61-90 days	9	101
> 90 days	0	14
Total past due	532	611
Non-accrual loans and leases	2,305	2,410
Loans aquired with deteriorated credit quality	0	0
Current loans	360,277	353,969
Total loans and leases	363,114	356,990
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	257	0
61-90 days	0	0
> 90 days	0	0
Total past due	257	0
Non-accrual loans and leases	5,885	6,332
Loans aquired with deteriorated credit quality	331	332
Current loans	156,836	145,269
Total loans and leases	163,309	151,933
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	4,207	2,020
61-90 days	10,045	0
> 90 days	0	0
Total past due	14,252	2,020
Non-accrual loans and leases	11,741	11,843
Loans aquired with deteriorated credit quality	1,881	949
Current loans	469,491	442,076
Total loans and leases	497,365	456,888
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	3,225	1,556
61-90 days	2,875	1,809
> 90 days	0	209
Total past due	6,100	3,574
Non-accrual loans and leases	5,413	13,681
Loans aquired with deteriorated credit quality	2,702	3,941
Current loans	549,043	550,314
Total loans and leases	563,258	571,510
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	5,889	5,443
61-90 days	139	1,603
> 90 days	0	0
Total past due	6,028	7,046
Non-accrual loans and leases	5,581	4,681
Loans aquired with deteriorated credit quality	0	0
Current loans	553,673	511,637
Total loans and leases	565,282	523,364
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	0	0
61-90 days	0	0
> 90 days	0	0
Total past due	0	0
Non-accrual loans and leases	2,558	3,125
Loans aquired with deteriorated credit quality	0	0
Current loans	114,178	117,189
Total loans and leases	$ 116,736	$ 120,314