Long-Term Debt (Details 2) (USD $)					9 Months Ended		1 Months Ended	3 Months Ended			1 Months Ended	9 Months Ended
	Jan. 01, 2012 Senior Credit Facility	Oct. 07, 2010 Senior Credit Facility	Jan. 01, 2012 Term A Loan due 2015	Oct. 07, 2010 Term A Loan due 2015	Jan. 01, 2012 Revolving Credit Facility due 2015	Oct. 07, 2010 Revolving Credit Facility due 2015	Oct. 31, 2011 2.75% Convertible Senior Subordinated Notes due 2011	Oct. 02, 2011 2.75% Convertible Senior Subordinated Notes due 2011	Jul. 03, 2011 2.75% Convertible Senior Subordinated Notes due 2011	Mar. 31, 2007 2.75% Convertible Senior Subordinated Notes due 2011	Sep. 30, 2010 6.875% Senior Subordinated Notes due 2020 Y	Jan. 01, 2012 6.875% Senior Subordinated Notes due 2020
Long-Term Debt
Aggregate principal amount				$ 400,000,000		$ 600,000,000				$ 300,000,000	$ 350,000,000
Senior Credit Facility, annual principal payments in first year				20,000,000
Senior Credit Facility, annual principal payments in second year				20,000,000
Senior Credit Facility, annual principal payments in third year				40,000,000
Senior Credit Facility, annual principal payments in fourth year				40,000,000
Senior Credit Facility, annual principal payments in fifth year				40,000,000
Base rate margin (as a percent)	1.25%
Eurodollar margin (as a percent)	2.25%
Weighted average interest rate (as a percent)			2.68%
Annual commitment fee on the unused portion (as a percent)					0.35%
Outstanding letters of credit					174,631,000
Available borrowing capacity					425,369,000
Debt issuance costs		12,800,000									7,100,000
Portion of debt which the holder chose to convert								3,000
Notes purchased from holders, aggregate principal amount							3,000	249,573,000	50,427,000
The number of shares per $1000 principal into which the debt can be converted								10.4208
Conversion ratio denominator, principal amount of Notes								$ 1
Conversion price (in dollars per share)								$ 95.96
Percentage of principal amount at which the entity may redeem some or all of the notes prior to September 15, 2015												100.00%
The maximum percentage of the principal amounts of the debt instrument which the entity may redeem with the proceeds of certain equity offerings prior to September 15, 2013												35.00%
Debt issuance cost amortization period (in years)											10
Percentage of principal amount of the debt instrument which the entity may redeem with the proceeds of certain equity offerings prior to September 15, 2013												106.875%