Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Drilling Commitments [Member]
Construction, Drilling and Purchase Commitments
Commitments for purchases and other expenditures	$ 192.0
Gathering Facilities And Pipelines Commitments [Member]
Construction, Drilling and Purchase Commitments
Commitments for purchases and other expenditures	6.6
Commitments To Secure Use Of Drilling Rigs [Member]
Construction, Drilling and Purchase Commitments
Commitments for purchases and other expenditures	$ 53.6