Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Recurring basis Total estimated fair value	Dec. 31, 2012 Recurring basis Total estimated fair value	Jun. 30, 2013 Recurring basis Total estimated fair value Forward fixed price purchase and sale contracts	Dec. 31, 2012 Recurring basis Total estimated fair value Forward fixed price purchase and sale contracts	Jun. 30, 2013 Recurring basis Total estimated fair value Swap agreements and option contracts	Dec. 31, 2012 Recurring basis Total estimated fair value Swap agreements and option contracts	Jun. 30, 2013 Recurring basis Total estimated fair value Interest rate cap	Dec. 31, 2012 Recurring basis Total estimated fair value Interest rate cap	Jun. 30, 2013 Recurring basis Total estimated fair value Interest rate collar and swap	Dec. 31, 2012 Recurring basis Total estimated fair value Interest rate collar and swap	Jun. 30, 2013 Recurring basis Total estimated fair value Foreign currency derivatives	Dec. 31, 2012 Recurring basis Total estimated fair value Foreign currency derivatives	Jun. 30, 2013 Recurring basis Total estimated fair value Inventories	Dec. 31, 2012 Recurring basis Total estimated fair value Inventories	Jun. 30, 2013 Recurring basis Level 1	Dec. 31, 2012 Recurring basis Level 1	Jun. 30, 2013 Recurring basis Level 1 Swap agreements and option contracts	Dec. 31, 2012 Recurring basis Level 1 Swap agreements and option contracts	Jun. 30, 2013 Recurring basis Level 2	Dec. 31, 2012 Recurring basis Level 2	Jun. 30, 2013 Recurring basis Level 2 Forward fixed price purchase and sale contracts	Dec. 31, 2012 Recurring basis Level 2 Forward fixed price purchase and sale contracts	Jun. 30, 2013 Recurring basis Level 2 Swap agreements and option contracts	Dec. 31, 2012 Recurring basis Level 2 Swap agreements and option contracts	Jun. 30, 2013 Recurring basis Level 2 Interest rate cap	Dec. 31, 2012 Recurring basis Level 2 Interest rate cap	Jun. 30, 2013 Recurring basis Level 2 Interest rate collar and swap	Dec. 31, 2012 Recurring basis Level 2 Interest rate collar and swap	Jun. 30, 2013 Recurring basis Level 2 Foreign currency derivatives	Dec. 31, 2012 Recurring basis Level 2 Foreign currency derivatives	Jun. 30, 2013 Recurring basis Level 2 Inventories	Dec. 31, 2012 Recurring basis Level 2 Inventories	Jun. 30, 2013 Recurring basis Level 3	Jun. 30, 2013 Recurring basis Level 3 Forward fixed price purchase and sale contracts
Assets:
Hedged inventories														$ 217,356	$ 526,107																	$ 217,356	$ 526,107
Derivative assets				2,022	48,062	129	179	92	35			380	145					126	54			2,022	48,062	3	125	92	35			380	145
Broker margin deposits		21,954	54,726													21,954	54,726
Pension plan		17,430	17,158													17,430	17,158
Total assets		259,363	646,412													39,510	71,938			219,853	574,474
Liabilities:
Derivative liabilities				(8,730)	(34,474)	(126)	(54)			(9,937)	(13,402)							(126)	(54)			(1,055)	(34,474)					(9,937)	(13,402)						(7,675)
Total liabilities		(18,793)	(47,930)													(126)	(54)			(10,992)	(47,876)													(7,675)
Changes in fair value of Level 3 financial assets
Reclass of Level 2 inputs	15,127
Change in fair value recorded in Cost of Sales	(22,802)
Fair value at the end of the period	$ (7,675)