Treasury Stock - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Oct. 31, 2014
Equity [Abstract]
Share repurchase new limit amount			$ 25,000,000
Share repurchase program expiration date	Dec. 31, 2015
Shares repurchased	1,258,250	1,258,250
Shares repurchased, value	$ 22,400,000
Shares repurchased, average price	$ 17.78