Segment Information (Details 3) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating income (loss)
Gross profit decrease from intra-company sales	$ 291,624,000	$ 288,512,000	$ 222,771,000	$ 163,304,000	$ 197,996,000	$ 197,192,000	$ 147,692,000	$ 176,264,000	$ 966,211,000	$ 719,144,000	$ 719,898,000
Assets elimination
Elimination of intra-company receivables	902,825,000				720,600,000				902,825,000	720,600,000
Other	97,529,000				115,083,000				97,529,000	115,083,000
Total assets	7,311,027,000				5,933,006,000				7,311,027,000	5,933,006,000	5,815,416,000
Liabilities elimination
Elimination of intra-company payables	511,056,000				414,932,000				511,056,000	414,932,000
Liabilities	4,389,160,000				3,320,637,000				4,389,160,000	3,320,637,000	3,338,760,000
Acquisition
Acquisition and related costs		25,000,000
Eliminations
Operating income (loss)
Gross profit decrease from intra-company sales									4,400,000	(900,000)	(3,300,000)
Assets elimination
Elimination of intra-company receivables	(60,300,000)				(43,500,000)				(60,300,000)	(43,500,000)	(41,400,000)
Elimination of intra-company debt	(137,100,000)				(159,300,000)				(137,100,000)	(159,300,000)	(141,100,000)
Other	(9,000,000)				(13,500,000)				(9,000,000)	(13,500,000)	(12,400,000)
Total assets	(206,437,000)				(216,295,000)				(206,437,000)	(216,295,000)	(194,868,000)
Liabilities elimination
Elimination of intra-company payables	(60,800,000)				(43,900,000)				(60,800,000)	(43,900,000)	(41,700,000)
Elimination of intra-company debt	(137,100,000)				(159,300,000)				(137,100,000)	(159,300,000)	(141,100,000)
Other	1,400,000				(800,000)				1,400,000	(800,000)	(1,500,000)
Liabilities	$ (196,468,000)				$ (203,945,000)				$ (196,468,000)	$ (203,945,000)	$ (184,341,000)