Credit Quality of Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	$ 11,660	$ 22,036
61-90 days	3,793	4,258
> 90 days	247	577
Total past due	15,700	26,871
Non-accrual loans and leases	47,548	71,680
Loans aquired with deteriorated credit quality	7,200
Current loans	2,460,680	2,141,141
Total loans and leases	2,531,128	2,239,692
Commercial Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	2,138	1,467
61-90 days	212	62
> 90 days	24	0
Total past due	2,374	1,529
Non-accrual loans and leases	4,611	7,226
Loans aquired with deteriorated credit quality	1,978
Current loans	337,745	251,572
Total loans and leases	346,708	260,327
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	7	7
61-90 days	68	0
> 90 days	0	2
Total past due	75	9
Non-accrual loans and leases	865	853
Loans aquired with deteriorated credit quality	0
Current loans	2,481	6,092
Total loans and leases	3,421	6,954
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	496	467
61-90 days	101	20
> 90 days	14	165
Total past due	611	652
Non-accrual loans and leases	2,410	1,786
Loans aquired with deteriorated credit quality	0
Current loans	353,969	357,642
Total loans and leases	356,990	360,080
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	0	717
61-90 days	0	0
> 90 days	0	0
Total past due	0	717
Non-accrual loans and leases	6,332	18,702
Loans aquired with deteriorated credit quality	332
Current loans	145,269	141,527
Total loans and leases	151,933	160,946
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	2,020	10,723
61-90 days	0	0
> 90 days	0	0
Total past due	2,020	10,723
Non-accrual loans and leases	11,843	16,963
Loans aquired with deteriorated credit quality	949
Current loans	442,076	344,262
Total loans and leases	456,888	371,948
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	1,556	1,677
61-90 days	1,809	2,537
> 90 days	209	0
Total past due	3,574	4,214
Non-accrual loans and leases	13,681	14,709
Loans aquired with deteriorated credit quality	3,941
Current loans	550,314	503,153
Total loans and leases	571,510	522,076
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	5,443	5,246
61-90 days	1,603	1,639
> 90 days	0	167
Total past due	7,046	7,052
Non-accrual loans and leases	4,681	5,722
Loans aquired with deteriorated credit quality	0
Current loans	511,637	435,888
Total loans and leases	523,364	448,662
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	0	1,732
61-90 days	0	0
> 90 days	0	243
Total past due	0	1,975
Non-accrual loans and leases	3,125	5,719
Loans aquired with deteriorated credit quality	0
Current loans	117,189	101,005
Total loans and leases	$ 120,314	$ 108,699