Segment Information (Details 3) (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	Dec. 31, 2010	Dec. 31, 2009
Operating income (loss)
Gross profit increase from intra-company sales	$ 160,135,000	$ 199,243,000	$ 276,386,000	$ 295,754,000	$ 133,668,000	$ 139,532,000	$ 191,984,000	$ 210,482,000	$ 931,518,000	$ 675,666,000	$ 399,076,000
Assets elimination
Elimination of intra-company receivables	722,791,000				622,189,000				722,791,000	622,189,000
Other	134,264,000				135,683,000				134,264,000	135,683,000
Total assets	5,979,226,000				5,589,934,000				5,979,226,000	5,589,934,000	5,129,872,000
Liabilities elimination
Elimination of intra-company payables	420,824,000				348,601,000				420,824,000	348,601,000
Liabilities	3,608,632,000				3,458,804,000				3,608,632,000	3,458,804,000	3,126,607,000
Eliminations
Operating income (loss)
Gross profit increase from intra-company sales									1,800,000	(3,500,000)	(20,300,000)
Assets elimination
Elimination of intra-company receivables	(36,100,000)				(36,000,000)				(36,100,000)	(36,000,000)	(27,000,000)
Elimination of intra-company debt	(152,800,000)				(134,800,000)				(152,800,000)	(134,800,000)	(174,900,000)
Other	(9,300,000)				(25,800,000)				(9,300,000)	(25,800,000)	400,000
Total assets	(198,248,000)				(196,557,000)				(198,248,000)	(196,557,000)	(201,460,000)
Liabilities elimination
Elimination of intra-company payables	(36,100,000)				(36,000,000)				(36,100,000)	(36,000,000)	(27,000,000)
Liabilities	(189,084,000)				(173,289,000)				(189,084,000)	(173,289,000)	(197,198,000)
Elimination of intra-company debt	(152,800,000)				(134,800,000)				(152,800,000)	(134,800,000)	(174,900,000)
Other liabilities	$ (200,000)				$ (2,500,000)				$ (200,000)	$ (2,500,000)	$ 4,700,000