Treasury Stock - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Jul. 28, 2011
Additional amount authorized by board of directors		$ 25,000
Authorized to repurchase common stock including additional repurchase		50,000
Authorized to repurchase common stock	25,000
Expiration date on repurchase authorizations	Sep. 30, 2013
Common stock acquired, shares	1,955
Aggregate cost shares of common stock	4,925
Shares repurchased during the period	298
Remaining authorized repurchase amount	21,181
Common Stock
Aggregate cost shares of common stock	$ 28,819