Derivative Financial Instruments (Schedule of Oil Derivative Contract Volumes And Weighted Average Prices) (Details) (Oil Contracts [Member])
Jun. 30, 2013
bbl
2013 Collar Contracts With Short Puts [Member]
 
Derivative [Line Items]  
Volume (BBLs per day) 1,750
Average Price, Ceiling 116.00
Average Price, Floor 88.14
2013 Collar Contracts With Short Puts [Member] | Short Put [Member]
 
Derivative [Line Items]  
Average Price, Short Put 73.14
2014 Collar Contracts With Short Puts [Member]
 
Derivative [Line Items]  
Volume (BBLs per day) 5,000
Average Price, Ceiling 105.74
Average Price, Floor 100.00
2014 Collar Contracts With Short Puts [Member] | Short Put [Member]
 
Derivative [Line Items]  
Average Price, Short Put 80.00
2013 Swap Contracts [Member]
 
Derivative [Line Items]  
Volume (BBLs per day) 3,000
Average Price, Fixed 81.02
Subsequent Event [Member] | August through December 2013 Swap Contracts [Member]
 
Derivative [Line Items]  
Volume (BBLs per day) 1,750
Average Price, Fixed 99.50