Gas Gathering and Processing Acquisitions and Divestitures (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 31, 2012	Nov. 01, 2011
Business Acquisition [Line Items]
Percentage of Membership Interest Acquired					100.00%
Purchase Price				$ 78.6	$ 200.4
Current Assets					5.4
Net Property, Plant and Equipment					24.3
Intangible Assets					136.3
Goodwill					39.4
Current Liabilities Assumed					(5.0)
Intangible Assets, Net (Excluding Goodwill)		127.4	137.0
Intangible Assets, Accumulated Amortization		14.5	4.9
Acquisition Related Costs, Sales Tax on Acquired Assets		3.5
Proceeds from Sale of Property, Plant, and Equipment	35.0		15.9
Gain on Sale of Property Plant Equipment	10.0		3.7
Customer Contracts [Member]
Business Acquisition [Line Items]
Intangible Assets, Net (Excluding Goodwill)		125.7	134.8
Intangible Assets, Accumulated Amortization		$ 10.6	$ 1.5