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]	Jun. 30, 2016	Dec. 31, 2015
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	80.40%	53.50%
Transportation cost	1.90%	0.00%
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	15.10%	17.90%
Transportation cost	4.30%	10.40%
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	15.90%	10.00%
Transportation cost	2.50%	1.80%
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	18.00%	17.70%
Transportation cost	5.10%	6.60%