Commitments and Contingencies (Details Textual) - USD ($) $ in Millions		12 Months Ended
	Feb. 27, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Obligations (Textual)
Operating Leases, Rent Expense		$ 16.8	$ 21.0	$ 20.5
Operating Lease Term of Contract	11 years
Operating Lease, Early Termination Option	7 years
Operating Leases, Future Minimum Payments Due		23.0
Operating lease commitments [Member]
Obligations (Textual)
Operating Leases, Future Minimum Payments Due		24.1
Operating Leases, Future Minimum Payments Due, Next Twelve Months		4.1
Operating Leases, Future Minimum Payments, Due in Two Years		3.3
Operating Leases, Future Minimum Payments, Due in Three Years		3.7
Operating Leases, Future Minimum Payments, Due in Four Years		3.9
Operating Leases, Future Minimum Payments, Due in Five Years		5.5
Gas transportation and processing obligations [Member]
Obligations (Textual)
Operating Leases, Future Minimum Payments Due		80.7
Operating Leases, Future Minimum Payments Due, Next Twelve Months		14.5
Operating Leases, Future Minimum Payments, Due in Two Years		17.7
Operating Leases, Future Minimum Payments, Due in Three Years		17.2
Operating Leases, Future Minimum Payments, Due in Four Years		16.9
Operating Leases, Future Minimum Payments, Due in Five Years		$ 14.3