Guarantor Financial Information (Condensed Consolidating Statements of Comprehensive Income) (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Net income	$ 37,172	$ 41,132	$ 101,968	$ 139,921
Other comprehensive income (loss):
Pension adjustments, net of tax	742	431	2,226	1,293
Total other comprehensive income	825	497	2,789	1,626
Total comprehensive income	37,997	41,629	104,757	141,547
Issuer [Member]
Net income	37,172	41,132	101,968	139,921
Other comprehensive income (loss):
Pension adjustments, net of tax	742	431	2,226	1,293
Total other comprehensive income	825	497	2,789	1,626
Total comprehensive income	37,997	41,629	104,757	141,547
Guarantors [Member]
Net income	33,249	36,736	93,596	121,165
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0	0	0
Total other comprehensive income	0	0	0	0
Total comprehensive income	33,249	36,736	93,596	121,165
Non-guarantors [Member]
Net income	(372)	14	(868)	(420)
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0	0	0
Total other comprehensive income	0	0	0	0
Total comprehensive income	(372)	14	(868)	(420)
Eliminations [Member]
Net income	(32,877)	(36,750)	(92,728)	(120,745)
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0	0	0
Total other comprehensive income	0	0	0	0
Total comprehensive income	(32,877)	(36,750)	(92,728)	(120,745)
Natural Gas Swap [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	83	(108)	404	(222)
Natural Gas Swap [Member] | Issuer [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	83	(108)	404	(222)
Natural Gas Swap [Member] | Guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0	0	0
Natural Gas Swap [Member] | Non-guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0	0	0
Natural Gas Swap [Member] | Eliminations [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0	0	0
Interest Rate Swap [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	174	159	555
Interest Rate Swap [Member] | Issuer [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	174	159	555
Interest Rate Swap [Member] | Guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0	0	0
Interest Rate Swap [Member] | Non-guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0	0	0
Interest Rate Swap [Member] | Eliminations [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	$ 0	$ 0	$ 0	$ 0