Stockholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity, Class of Treasury Stock [Line Items]
Authorized number of common shares to purchase, maximum	4,000,000
Shares repurchased during period	0	0	0
Number of treasury shares held		59,912
Average cost of treasury stock, per share		$ 11.00