Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$ 173.5	$ 173.5	$ 0
Non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of gas gathering and processing equipment		1.7		21.4
Impairment of casing inventory		$ 0.2	$ 1.1	$ 1.2