Derivative Instruments (Schedule Of U.S. Natural Gas Derivative Positions) (Details) (Natural Gas Derivative Positions [Member])	Dec. 31, 2013 MMBTU
2014 [Member] | Swaps [Member]
Derivative [Line Items]
Volume (in MMBtu/d)	45,000
Weighted Average Floor Price ($/MMBtu)	4.09
Weighted Average Ceiling Price ($/MMBtu)
2014 [Member] | Calls [Member]
Derivative [Line Items]
Volume (in MMBtu/d)	10,000
Weighted Average Ceiling Price ($/MMBtu)	5.50
2015 [Member] | Swaps [Member]
Derivative [Line Items]
Volume (in MMBtu/d)	10,000
Weighted Average Floor Price ($/MMBtu)	4.33