Long-Term Debt (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		0 Months Ended					0 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 30, 2012 Senior unsecured notes	Oct. 21, 2011 Senior unsecured notes	Aug. 16, 2005 Senior unsecured notes	Mar. 31, 2013 Capital lease obligations	Dec. 31, 2012 Capital lease obligations	Mar. 30, 2012 2012 Credit Agreement	Feb. 29, 2012 2008 Credit Facility	Oct. 21, 2011 2008 Credit Facility
Long-term debt
Senior unsecured notes issued					$ 150,000
Interest rate on senior unsecured notes (as a percent)					7.625%
Value of senior notes redeemed		100,000	100,000	50,000
Proceeds used to redeem senior notes	20,120	230,797						103,495		51,271
Premium paid			2,542	1,271
Unamortized deferred financing costs written off		1,220	1,087	623					133
Long term debt interest expense
Interest expense	1,756	3,255
Change in the fair value of non-hedged derivative instruments	(181)	(89)
Amortization of deferred financing costs	90	176
Interest expense, including the change in fair value of non-hedged derivative instruments and amortization of deferred financing costs	1,665	3,342
Company's debt and capital lease obligations
Capital lease obligations						2,272	2,425
2013 (nine months)	902
2014	831
2015	321
2016	209
2017	190,327
Company's debt and capital lease obligations, Total	$ 192,590