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. 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 adjustments	(10,146)				10,146
Derivative adjustments							712	712	(482)	(482)	0
Foreign currency translation adjustments, net of tax	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 adjustments	(1,169)				(1,169)
Derivative adjustments							159	159	391	391	194	194
Foreign currency translation adjustments, net of tax	0
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
Net income	108,967					108,967
Pension adjustments	15,140				15,140
Derivative adjustments							0		127	127	1,141	1,141
Foreign currency translation adjustments, net of tax	(14,502)				(14,502)
Issuance of non-vested stock (in shares)		387,681
Issuance of non-vested stock	6,539	4	6,535
Stock-based compensation	50		50
Tax benefits associated with stock-based compensation	1,138		1,138
Treasury stock (in shares)		(185,919)
Treasury stock	(3,238)			(3,238)
Issuance of common stock (in shares)		46,250,672
Issuance of common stock	843,154	463	842,691
Balance at Dec. 28, 2013	$ 2,020,952	$ 1,653	$ 1,454,250	$ (13,271)	$ (29,423)	$ 607,743
Balance (in shares) at Dec. 28, 2013		164,267,425