Guarantor Financial Information (Condensed Consolidating Statements of Comprehensive Income) (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Net income	$ 32,405	$ 28,571
Other comprehensive income (loss):
Pension adjustments, net of tax	805	742
Total other comprehensive income	1,902	891
Total comprehensive income	34,307	29,462
Issuer [Member]
Net income	32,405	28,571
Other comprehensive income (loss):
Pension adjustments, net of tax	805	742
Total other comprehensive income	1,902	891
Total comprehensive income	34,307	29,462
Guarantors [Member]
Net income	30,435	30,474
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0
Total other comprehensive income	0	0
Total comprehensive income	30,435	30,474
Non-guarantors [Member]
Net income	(717)	(142)
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0
Total other comprehensive income	0	0
Total comprehensive income	(717)	(142)
Eliminations [Member]
Net income	(29,718)	(30,332)
Other comprehensive income (loss):
Pension adjustments, net of tax	0	0
Total other comprehensive income	0	0
Total comprehensive income	(29,718)	(30,332)
Natural Gas Swap [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	148	7
Natural Gas Swap [Member] | Issuer [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	148	7
Natural Gas Swap [Member] | Guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0
Natural Gas Swap [Member] | Non-guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0
Natural Gas Swap [Member] | Eliminations [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	0
Corn Option [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	949	0
Corn Option [Member] | Issuer [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	949
Corn Option [Member] | Guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0
Corn Option [Member] | Non-guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0
Corn Option [Member] | Eliminations [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0
Interest Rate Swap [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax	0	142
Interest Rate Swap [Member] | Issuer [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax		142
Interest Rate Swap [Member] | Guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax		0
Interest Rate Swap [Member] | Non-guarantors [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax		0
Interest Rate Swap [Member] | Eliminations [Member]
Other comprehensive income (loss):
Derivative adjustments, net of tax		$ 0