Fair Value Measurements (Unobservable Inputs In Level 3 Valuations Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (Weighted Average [Member], Significant Unobservable Inputs (Level 3) [Member], Fair Value, Measurements, Recurring [Member])	Mar. 31, 2015	Dec. 31, 2014
Inventory Related Payables [Member]
Unobservable inputs in Level 3 Valuations of Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Basis	40.10%	43.40%
Transportation cost	2.20%	15.20%
Commodity Derivative Contracts Losses [Member]
Unobservable inputs in Level 3 Valuations of Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Basis	20.80%	13.60%
Transportation cost	16.40%	19.50%
Inventories Carried At Market [Member]
Unobservable inputs in Level 3 Valuations of Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Basis	18.10%	23.40%
Transportation cost	3.00%	4.90%
Commodity Derivative Contracts Gains [Member]
Unobservable inputs in Level 3 Valuations of Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Basis	22.40%	13.50%
Transportation cost	3.80%	10.20%