Derivative Financial Instruments (Schedule Of NYMEX Contracts And Butane Price Swap Purchase Agreements) (Details) - bbl bbl in Millions	Dec. 31, 2015	Dec. 31, 2014
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	0.0
Fair Value Hedging [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	0.7
Fair Value Hedging [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	0.7	0.7
Economic Hedges [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	4.5
Economic Hedges Futures [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	0.9