Commitments and Contingencies Additional information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	3 Months Ended
	Dec. 31, 2014	Mar. 31, 2015
Loss Contingencies [Line Items]
Accrued Environmental Liabilities	$ 0.8	$ 3.6
Partnership Class Action
Loss Contingencies [Line Items]
Litigation Settlement Amount	37.5
PDC Payment | Partnership Class Action
Loss Contingencies [Line Items]
Litigation Settlement Amount		31.5
Insurance Payment | Partnership Class Action
Loss Contingencies [Line Items]
Litigation Settlement Amount		$ 6.0