Pending Merger and Acquisition - Additional Information (Detail) (Coastal Bankshares, Inc. [Member], USD $)	0 Months Ended		12 Months Ended
	Mar. 10, 2014 Location	Feb. 28, 2014	Dec. 31, 2013	Mar. 31, 2014
Coastal Bankshares, Inc. [Member]
Business Acquisition [Line Items]
Number of banking locations	6
Merger agreement date	Mar. 10, 2014
Reported assets of Coastal Bank			$ 433,000,000
Reported loans of Coastal Bank			295,000,000
Reported deposits of Coastal Bank			364,000,000
Shares to receive for each share of Coastal common stock pursuant to the merger agreement				0.4671
Transaction amount		$ 37,300,000
Transaction value as a percentage of tangible book value			169.00%