Segment Information (Details 3) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating income (loss)
Gross profit reduction from intra-company sales	$ 180,097,000	$ 156,401,000	$ 182,136,000	$ 201,264,000	$ 160,135,000	$ 199,243,000	$ 276,386,000	$ 295,754,000	$ 719,898,000	$ 931,518,000	$ 675,666,000
Assets elimination
Elimination of intra-company receivables	642,363,000				722,791,000				642,363,000	722,791,000
Other	132,816,000				134,264,000				132,816,000	134,264,000
Total assets	5,815,416,000				5,979,226,000				5,815,416,000	5,979,226,000	5,589,934,000
Liabilities elimination
Elimination of intra-company payables	360,097,000				420,824,000				360,097,000	420,824,000
Liabilities	3,338,760,000				3,608,632,000				3,338,760,000	3,608,632,000	3,458,804,000
Eliminations
Operating income (loss)
Gross profit reduction from intra-company sales									(3,300,000)	1,800,000	(3,500,000)
Assets elimination
Elimination of intra-company receivables	(41,400,000)				(36,100,000)				(41,400,000)	(36,100,000)	(36,000,000)
Elimination of intra-company debt	(141,100,000)				(152,800,000)				(141,100,000)	(152,800,000)	(134,800,000)
Other	(12,400,000)				(9,300,000)				(12,400,000)	(9,300,000)	(25,800,000)
Total assets	(194,868,000)				(198,248,000)				(194,868,000)	(198,248,000)	(196,557,000)
Liabilities elimination
Elimination of intra-company payables	(41,700,000)				(36,100,000)				(41,700,000)	(36,100,000)	(36,000,000)
Elimination of intra-company debt	(141,100,000)				(152,800,000)				(141,100,000)	(152,800,000)	(134,800,000)
Other liabilities	(1,500,000)				(200,000)				(1,500,000)	(200,000)	(2,500,000)
Liabilities	$ (184,341,000)				$ (189,084,000)				$ (184,341,000)	$ (189,084,000)	$ (173,289,000)