Business Segments (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011 Segment	Dec. 31, 2010	Dec. 31, 2009
Business Segments
Number of reportable segments									2
Business Segments
Net sales	$ 1,062,168,000	$ 1,351,964,000	$ 1,447,716,000	$ 1,167,265,000	$ 1,148,184,000	$ 1,031,174,000	$ 1,005,898,000	$ 894,512,000	$ 5,029,113,000	$ 4,079,768,000	$ 3,136,329,000
Cost of product sold (exclusive of depreciation and amortization)	857,277,000	1,026,040,000	1,123,375,000	936,822,000	983,726,000	889,850,000	891,652,000	802,890,000	3,943,514,000	3,568,118,000	2,547,695,000
Direct operating expenses (exclusive of depreciation and amortization)	124,796,000	74,615,000	66,207,000	68,434,000	64,216,000	52,534,000	62,479,000	60,562,000	334,052,000	239,791,000	226,657,000
Depreciation and amortization	24,242,000	22,025,000	22,043,000	22,011,000	22,005,000	21,943,000	21,553,000	21,260,000	90,321,000	86,761,000	84,873,000
Operating income	26,880,000	212,190,000	217,920,000	109,606,000	34,787,000	50,450,000	19,421,000	(11,594,000)	566,596,000	93,064,000	208,186,000
Capital expenditures									91,224,000	32,409,000	48,773,000
Total assets	3,119,291,000				1,740,184,000				3,119,291,000	1,740,184,000	1,614,494,000
Goodwill	40,969,000				40,969,000				40,969,000	40,969,000	40,969,000
Petroleum
Business Segments
Intercompany sales									11,400,000	4,300,000	6,100,000
Intercompany cost of product sold (exclusive of depreciation and amortization)									13,200,000	(1,600,000)	(800,000)
Net sales									4,751,826,000	3,903,826,000	2,934,904,000
Cost of product sold (exclusive of depreciation and amortization)									3,926,632,000	3,538,017,000	2,514,293,000
Direct operating expenses (exclusive of depreciation and amortization)									247,665,000	153,112,000	142,204,000
Depreciation and amortization									69,852,000	66,391,000	64,424,000
Operating income									465,710,000	104,564,000	170,184,000
Capital expenditures									68,612,000	19,761,000	34,018,000
Total assets	2,322,148,000				1,049,361,000				2,322,148,000	1,049,361,000	1,082,707,000
Nitrogen Fertilizer
Business Segments
Intercompany sales									14,200,000	100,000	800,000
Intercompany cost of product sold (exclusive of depreciation and amortization)									10,700,000	4,000,000	7,900,000
Cost of product sold related to the transfer of excess hydrogen									1,000,000	1,800,000	1,600,000
Net sales									302,867,000	180,468,000	208,371,000
Cost of product sold (exclusive of depreciation and amortization)									42,511,000	34,328,000	42,158,000
Direct operating expenses (exclusive of depreciation and amortization)									86,491,000	86,679,000	84,453,000
Depreciation and amortization									18,869,000	18,463,000	18,685,000
Operating income									136,198,000	20,356,000	48,863,000
Capital expenditures									19,144,000	10,117,000	13,389,000
Total assets	659,309,000				452,165,000				659,309,000	452,165,000	702,929,000
Goodwill	40,969,000				40,969,000				40,969,000	40,969,000	40,969,000
Other
Business Segments
Direct operating expenses (exclusive of depreciation and amortization)									(104,000)
Depreciation and amortization									1,600,000	1,907,000	1,764,000
Operating income									(35,312,000)	(31,856,000)	(10,861,000)
Capital expenditures									3,468,000	2,531,000	1,366,000
Total assets	137,834,000				238,658,000				137,834,000	238,658,000	(171,142,000)
Intersegment elimination
Business Segments
Net sales									(25,580,000)	(4,526,000)	(6,946,000)
Cost of product sold (exclusive of depreciation and amortization)									$ (25,629,000)	$ (4,227,000)	$ (8,756,000)