Participation in Treasury Capital Purchase Program - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended		6 Months Ended
	Jul. 03, 2012	Jan. 23, 2009	Jun. 30, 2013
Equity [Abstract]
Sale to U.S. Treasury of newly-issued non-voting preferred shares		$ 23,184
Number of shares issued and sold to Treasury		23,184
Liquidation preference as per securities purchase agreement		$ 1,000
Warrant sold to purchase common shares as per securities purchase agreement		469,312
Amount of common shares not considered in computing diluted earnings per common share		7.41
Term of Warrant			10 years
Liquidation preference rate for first five years			5.00%
Liquidation preference rate after five years			9.00%
Sale of Preferred Shares to investors	23,184