Acquisition - Additional Information (Detail) (USD $)	6 Months Ended		1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	May 31, 2012 CommerceFirst Bancorp, Inc.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Business acquisition, percentage of common stock acquired			100.00%
Business acquisition, percentage of commons stock acquired in exchange of common stock			50.00%
Business acquisition, percentage of common stock acquired in exchange of cash			50.00%
Stock consideration, exchange ratio			0.8043
Business acquisition, common stock issued			732,054
Business acquisition, cash consideration paid			$ 12,381,000
Business acquisition, cash consideration paid per share			$ 13.60
Business acquisition, asset acquired			190,899,000
Business acquisition, loans and leases acquired			168,984,000
Business acquisition, liabilities assumed			170,565,000
Business acquisition, liabilities assumed in deposits			169,921,000
Business acquisition, addition to Company's equity	13,023,000		13,000,000
Business acquisition, goodwill			5,070,000
Business acquisition, pro forma revenue, net of interest expense	85,800,000	82,600,000
Business acquisition, pro forma net income	$ 16,100,000	$ 16,500,000