Debt (Details) (USD $)	3 Months Ended		3 Months Ended						3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013 Minimum	Jun. 30, 2013 Senior Notes due 2018 item	Mar. 31, 2013 Senior Notes due 2018	Jun. 30, 2013 Revolving credit facility	Mar. 31, 2013 Revolving credit facility	Jun. 29, 2012 Revolving credit facility	Jun. 30, 2013 U.S. revolving credit facility	Jun. 30, 2013 Canadian revolving credit facility
Debt
Long-term debt	$ 654,790,000	$ 708,790,000		$ 643,790,000	$ 643,790,000	$ 11,000,000	$ 65,000,000
Less portion classified as current	(11,000,000)	(65,000,000)
Long-term debt, less current portion	643,790,000	643,790,000
Interest rate (as a percent)				8.875%
Principal payments required prior to maturity				0
Estimated fair value of debt				686,000,000	669,500,000
Number of preceding quarters for which fixed charge coverage ratio is measured				4
Amount permitted to be distributed by the indenture under the limitation				275,800,000
Minimum fixed charge coverage ratio required to make restricted payments	1.75			1.75
Actual fixed charge coverage ratio	2.10			2.10
Amount included in the general basket of restricted payments				75,000,000
Maximum borrowing capacity						400,000,000		400,000,000	200,000,000	200,000,000
Amount by which maximum borrowing capacity may be expanded in additional commitments									100,000,000	100,000,000
Borrowing base collateral						326,500,000
Borrowings outstanding	11,000,000	65,000,000				11,000,000
Weighted average interest rate (as a percent)						6.00%
Letters of credit issued						$ 25,400,000	$ 3,300,000
Fixed charge coverage ratio required to incur additional debt obligations			2.0