Derivative Instruments (Schedule Of U.S. Crude Oil Derivative Positions) (Details) (U.S. Crude Oil Derivative Positions [Member])	Mar. 31, 2014 bbls
Swaps [Member] | 2014 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	8,850
Weighted Average Floor Price ($/Bbls)	92.53
Weighted Average Ceiling Price ($/Bbls)
Swaps [Member] | 2015 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	5,200
Weighted Average Floor Price ($/Bbls)	91.44
Weighted Average Ceiling Price ($/Bbls)
Collars [Member] | 2014 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	3,000
Weighted Average Floor Price ($/Bbls)	88.33
Weighted Average Ceiling Price ($/Bbls)	104.26
Collars [Member] | 2015 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	700
Weighted Average Floor Price ($/Bbls)	90.00
Weighted Average Ceiling Price ($/Bbls)	100.65
Three-way Collars [Member] | 2014 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	500
Weighted Average Floor Price ($/Bbls)	85.00
Weighted Average Ceiling Price ($/Bbls)	107.75
Weighted Average Short Put Price ($/Bbl)	65.00
Weighted Average Put Spread ($/Bbl)	20.00
Three-way Collars [Member] | 2015 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	1,000
Weighted Average Floor Price ($/Bbls)	85.00
Weighted Average Ceiling Price ($/Bbls)	105.00
Weighted Average Short Put Price ($/Bbl)	65.00
Weighted Average Put Spread ($/Bbl)	20.00
Three-way Collars [Member] | 2016 [Member]
Derivative [Line Items]
Volumes (in Bbls/d)	667
Weighted Average Floor Price ($/Bbls)	85.00
Weighted Average Ceiling Price ($/Bbls)	104.00
Weighted Average Short Put Price ($/Bbl)	65.00
Weighted Average Put Spread ($/Bbl)	20.00