Financial Instruments (Changes in Level 3 Inputs) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Hypothetical change to estimated future cash flows attributable to commodity price swaps, percent	10.00%
Estimated change in fair value resulting from hypothetical percentage change in future cash flows attributable to commodity price swaps			$ 3,700,000
Commodity Contract [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, January 1, 2013	(6,249,000)	(149,278,000)	(33,658,000)	31,616,000
Unrealized (gains) losses included in other comprehensive income	50,615,000	248,572,000	1,413,000	33,553,000
Change in Fair Value Recognized in Cost of Product Sold	3,662,000	0	47,222,000	0
Settlements Recognized in Sales and Other Revenues	(3,868,000)	20,167,000	15,316,000	54,292,000
Settlements Recognized in Cost of Product Sold	(7,034,000)		6,833,000
Ending balance, June 30, 2013	$ 37,126,000	$ 119,461,000	$ 37,126,000	$ 119,461,000