Share Repurchases (Details) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2012	Jan. 01, 2012 Y	Mar. 31, 2009	Aug. 05, 2008
Share Repurchases
Number of shares authorized to repurchase				5,000,000
The limit of repurchase of common stock authorized	$ 200,000,000
Share repurchase program duration (in years)		2
Number of shares repurchased		742,000	299,956
Amount paid for repurchased shares (in dollars)		$ 49,991,000	$ 31,609,000
Remaining number of shares authorized to be repurchased		3,958,044