Litigation (Detail) - CommerceFirst Bank - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Loss Contingency, Name of Plaintiff		CommerceFirst Bank
Loss Contingency, Settlement Agreement, Date		6/30/2014
Loss Contingency Accrual			$ 6.5
Loss Contingency Accrual, Increase (Decrease)	$ (4.5)
Business Acquisition, Effective Date of Acquisition		Dec. 31, 2012