Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Inventory	$ 66.0	$ 44.5
Estimated Cost to Build	180.0
Goodwill, Acquired During Period	2.4
Proceeds from sale of assets	972.7	2.7	$ 69.1
Debt Issuance Costs, Net	34.0	40.9
Property Plant and Equipment Disposition	1,127.6
Indefinite-lived Intangible Assets (Excluding Goodwill), Fair Value Disclosure	3.7
Property, plant and equipment	2,555.4	3,747.7
Deferred revenue	$ 7.5	$ 14.2
Percentage of gross income from qualifying sources required to be subject to federal income tax, minimum	90.00%
Discount rate	19.00%	15.00%
Increase (Decrease) in Intangible Assets, Current	$ 8.5
Goodwill impairment	162.6	$ 1,406.3	48.8
Increase (Decrease) in Other Current Assets and Liabilities, Net	11.2
Granite Wash
Summary Of Significant Accounting Policies [Line Items]
Impaired assets to be disposed of		8.5	13.2
Fair value disclosure		11.2
Impairment of intangible assets			20.0
Goodwill impairment	0.0	0.0	14.2
Barnett
Summary Of Significant Accounting Policies [Line Items]
Impaired assets to be disposed of		354.4
Fair value disclosure		298.5
Impairment of intangible assets		238.9
Goodwill impairment	0.0	257.2	0.0
Fayetteville
Summary Of Significant Accounting Policies [Line Items]
Impaired assets to be disposed of		61.9
Fair value disclosure		59.3
Impairment of intangible assets		70.9
Goodwill impairment	0.0	72.5	4.3
Haynesville
Summary Of Significant Accounting Policies [Line Items]
Impaired assets to be disposed of		45.7
Fair value disclosure		3.8
Impairment of intangible assets		6.0
Watkins Glen
Summary Of Significant Accounting Policies [Line Items]
Impaired assets to be disposed of	31.2
Fair value disclosure		6.7
Trucking
Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets	31.4
Goodwill impairment	29.5	148.4	0.0
Natural Gas Liquids
Summary Of Significant Accounting Policies [Line Items]
Inventory	56.7	35.4
CMLP
Summary Of Significant Accounting Policies [Line Items]
Inventory	66.0	44.5
Goodwill, Acquired During Period	2.4
Proceeds from sale of assets	972.7	2.7	2.7
Property, plant and equipment	2,885.5	4,077.7
Deferred revenue	7.5	14.2
Goodwill impairment	$ 162.6	1,149.1	$ 48.8
Jackalope Gas Gathering Services, LLC
Summary Of Significant Accounting Policies [Line Items]
Equity method investment, other than temporary impairment		51.4
Powder River Basin Industrial Complex, LLC
Summary Of Significant Accounting Policies [Line Items]
Equity method investment, other than temporary impairment		$ 23.4
Minimum
Summary Of Significant Accounting Policies [Line Items]
Discount rate	10.00%	10.00%	9.00%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Discount rate	19.00%	16.00%	12.00%
Equity Method Investments [Member]
Summary Of Significant Accounting Policies [Line Items]
Discount rate		15.50%
Stagecoach Gas Services LLC
Summary Of Significant Accounting Policies [Line Items]
Equity method ownership percentage	50.00%
Stagecoach Gas Services LLC | CEGP [Member]
Summary Of Significant Accounting Policies [Line Items]
Proceeds from sale of assets	$ 975.0
Stagecoach Gas Services LLC | CMLP
Summary Of Significant Accounting Policies [Line Items]
Equity method ownership percentage	50.00%