Consolidated Statements of Stockholders’ Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Interest Rate Swap [Member]	Interest Rate Swap [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Natural Gas Swap [Member]	Natural Gas Swap [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Corn Option [Member]	Corn Option [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Jan. 02, 2010	$ 284,877	$ 826	$ 157,343	$ (3,855)	$ (23,782)	$ 154,345
Balance (in shares) at Jan. 02, 2010		82,226,690
Net income	44,243					44,243
Pension liability adjustments, net of tax	(2,346)				2,346
Derivative adjustments							507	507	(59)	(59)	0
Issuance of non-vested stock (in shares)		254,220
Issuance of non-vested stock	2,404	3	2,401
Stock-based compensation	94		94
Tax benefits associated with stock-based compensation	234		234
Treasury stock (in shares)		(51,740)
Treasury stock	(485)			(485)
Issuance of common stock (in shares)		10,130,501
Issuance of common stock	130,135	101	130,034
Balance at Jan. 01, 2011	464,296	930	290,106	(4,340)	(20,988)	198,588
Balance (in shares) at Jan. 01, 2011		92,559,671
Net income	169,418					169,418
Pension liability adjustments, net of tax	10,146				(10,146)
Derivative adjustments							712	712	(482)	(482)	0
Issuance of non-vested stock (in shares)		174,285
Issuance of non-vested stock	2,540	2	2,538
Stock-based compensation	492		492
Tax benefits associated with stock-based compensation	1,125		1,125
Treasury stock (in shares)		(88,364)
Treasury stock	(1,248)			(1,248)
Issuance of common stock (in shares)		24,402,846
Issuance of common stock	293,668	244	293,424
Balance at Dec. 31, 2011	920,375	1,176	587,685	(5,588)	(30,904)	368,006
Balance (in shares) at Dec. 31, 2011		117,048,438
Net income	130,770					130,770
Pension liability adjustments, net of tax	1,169				(1,169)
Derivative adjustments							159	159	391	391	194	194
Issuance of non-vested stock (in shares)		486,697
Issuance of non-vested stock	6,813	5	6,808
Stock-based compensation	3,727		3,727
Tax benefits associated with stock-based compensation	2,652		2,652
Treasury stock (in shares)		(264,275)
Treasury stock	(4,445)			(4,445)
Issuance of common stock (in shares)		544,131
Issuance of common stock	2,969	5	2,964
Balance at Dec. 29, 2012	$ 1,062,436	$ 1,186	$ 603,836	$ (10,033)	$ (31,329)	$ 498,776
Balance (in shares) at Dec. 29, 2012		117,814,991