Subsequent Events - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended						52 Months Ended	1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Stock Repurchase Program	Dec. 31, 2011 Stock Repurchase Program	Dec. 31, 2010 Stock Repurchase Program	Dec. 31, 2012 Stock Repurchase Program	Feb. 28, 2013 Subsequent Event Stock Repurchase Program	Jan. 31, 2013 Subsequent Event Phantom Stock	Jan. 31, 2013 Subsequent Event Restricted Stock
Subsequent Event [Line Items]
Shares or units awarded to certain employees									4,485	86,143
Fair value of the stock award on the date of grant									$ 361	$ 6,942
Vesting period										3 years
Repurchased and retired, shares				60,000	55,000	19,500	1,877,576	30,000
Repurchased and retired, aggregate price	$ 5,727	$ 6,649	$ 1,212	$ 5,727	$ 6,649	$ 1,212	$ 78,301	$ 2,683