Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 MMBTU	Dec. 31, 2012	Dec. 31, 2011
Commitements And Contingencies Disclosure [Abstract]
Commitment capacity per day of natural gas	200
Increased commitment capacity per day of natural gas	50
Demand charges related to remaining contract	$ 569.7
Initial Term Liquids Gathering System Lease	15
Renewal Term Liquids Gathering System Lease	5
Renewal Term Liquids Gathering System Lease Useful Life	75.00%
Liquids Gathering System Operating Lease Rental Expense	20.0
Lease And Rental Expense Total	283.8
Committed drilling obligations with rig contractors, total	56.5
Committed drilling obligations with rig contractors, due in one year	35.9
Committed drilling obligations with rig contractors, due in one to three years	20.6
Office Space Operating Lease Total Future Minimum Payments	2.2
Commitment to office leases, current	0.8
Commitment to office leases, due in three years	0.6
Commitment to office leases, due in five years	0.6
Commitment to office leases, due after five years	0.2
Office leases expense	$ 1.0	$ 1.0	$ 0.9