Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Jun. 24, 2014	Jun. 19, 2014
Changes in fair value of Level 3 financial assets
Estimates Margin for Transportation and Throughput Costs Per Barrel	7.45	10.75
Senior Notes 6.25 Percent Due 2022
Liabilities:
Stated interest rate (as a percent)	6.25%			6.25%	6.25%
Carrying value of debt instrument	$ 375,000		$ 375,000		$ 375,000
Fair value of debt instrument	365,411		358,594
Level 3
Changes in fair value of Level 3 financial assets
Fair value at the beginning of the period	(25,523)
Realized and unrealized gains (losses) recorded in cost of sales	10,634
Fair value at the end of the period	(14,889)
Recurring basis
Assets:
Total assets	(44,512)		(104,292)
Recurring basis | Exchange-Traded Derivatives
Assets:
Cash Collateral Netting	(44,512)		(104,292)
Recurring basis | Total estimated fair value
Assets:
Pension plans	17,316		18,023
Total assets	108,567		119,073
Liabilities:
Total liabilities	(54,921)		(65,203)
Recurring basis | Total estimated fair value | Forward derivative contracts
Assets:
Derivative assets	57,470		83,826
Liabilities:
Derivative liabilities	(47,567)		(56,428)
Recurring basis | Total estimated fair value | Swap agreements and option contracts
Liabilities:
Derivative liabilities	(705)		(2,079)
Recurring basis | Total estimated fair value | Interest rate cap
Assets:
Derivative assets	17		17
Recurring basis | Total estimated fair value | Exchange-Traded Derivatives
Assets:
Exchange-traded/cleared derivative instruments	33,737		17,198
Recurring basis | Total estimated fair value | Interest rate swaps
Liabilities:
Derivative liabilities	(6,649)
Recurring basis | Total estimated fair value | Foreign currency derivatives
Assets:
Derivative assets	27		9
Recurring basis | Total estimated fair value | Interest rate swaps
Liabilities:
Derivative liabilities			(6,696)
Recurring basis | Level 1
Assets:
Pension plans	17,316		18,023
Total assets	95,565		139,513
Recurring basis | Level 1 | Exchange-Traded Derivatives
Assets:
Exchange-traded/cleared derivative instruments	78,249		121,490
Recurring basis | Level 2
Assets:
Total assets	50,419		81,447
Liabilities:
Total liabilities	(32,937)		(37,275)
Recurring basis | Level 2 | Forward derivative contracts
Assets:
Derivative assets	50,375		81,421
Liabilities:
Derivative liabilities	(25,583)		(28,500)
Recurring basis | Level 2 | Swap agreements and option contracts
Liabilities:
Derivative liabilities	(705)		(2,079)
Recurring basis | Level 2 | Interest rate cap
Assets:
Derivative assets	17		17
Recurring basis | Level 2 | Interest rate swaps
Liabilities:
Derivative liabilities	(6,649)		(6,696)
Recurring basis | Level 2 | Foreign currency derivatives
Assets:
Derivative assets	27		9
Recurring basis | Level 3
Assets:
Total assets	7,095		2,405
Liabilities:
Total liabilities	(21,984)		(27,928)
Recurring basis | Level 3 | Forward derivative contracts
Assets:
Derivative assets	7,095		2,405
Liabilities:
Derivative liabilities	$ (21,984)		$ (27,928)