Credit Quality of Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	$ 20,394	$ 22,036
61-90 days	3,675	4,258
> 90 days	604	577
Total past due	24,673	26,871
Non-accrual loans and leases	55,567	71,680
Current loans	2,394,838	2,141,141
Total loans and leases	2,475,078	2,239,692
Commercial Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	4,466	1,467
61-90 days	341	62
> 90 days	70
Total past due	5,584	1,529
Non-accrual loans and leases	4,583	7,226
Current loans	324,580	251,572
Total loans and leases	334,040	260,327
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	7	7
61-90 days	4
> 90 days	96	2
Total past due	107	9
Non-accrual loans and leases	872	853
Current loans	4,639	6,092
Total loans and leases	5,618	6,954
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	1,015	467
61-90 days	80	20
> 90 days	5	165
Total past due	1,100	652
Non-accrual loans and leases	1,651	1,786
Current loans	354,783	357,642
Total loans and leases	357,534	360,080
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days		717
> 90 days	342
Total past due	342	717
Non-accrual loans and leases	13,055	18,702
Current loans	138,223	141,527
Total loans and leases	151,620	160,946
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	4,130	10,723
61-90 days	247
Total past due	4,377	10,723
Non-accrual loans and leases	13,327	16,963
Current loans	425,533	344,262
Total loans and leases	443,237	371,948
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	4,223	1,677
61-90 days	456	2,537
Total past due	4,679	4,214
Non-accrual loans and leases	15,146	14,709
Current loans	559,987	503,153
Total loans and leases	579,812	522,076
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	5,841	5,246
61-90 days	1,651	1,639
> 90 days	91	167
Total past due	7,583	7,052
Non-accrual loans and leases	2,600	5,722
Current loans	462,243	435,888
Total loans and leases	472,426	448,662
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60 days	712	1,732
61-90 days	896
> 90 days		243
Total past due	1,608	1,975
Non-accrual loans and leases	4,333	5,719
Current loans	124,850	101,005
Total loans and leases	$ 130,791	$ 108,699