Acquisitions, Joint Ventures, and Divestitures (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Schedule of Equity Method Investments - Acquisitions [Line Items]
Amount reserved for investment in a cash escrow account, included in Restricted Deposits at year end	$ 0.7	$ 50.0
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent interest of Kinderhawk purchased	0.50
Percent interest in Petrohawk's gathering assets acquired	0.25
Aggregate consideration paid for Kinderhawk and Petrohawk's gathering assets	912.1
Cash consideration paid for Kinderhawk and Petrohawk's gathering assets	835.1
Debt assumed as part of acquisition of Kinderhawk and Petrohawk's gathering assets	77.0
Amount of Kinderhawk's debt paid off following acquisition	154.0
Miles of pipe owned and operated by Kinderhawk	400
Kinderhawk's pipeline capacity in bcf per day	2.0
Kinderhawk's current utilization in bcf per day	1.0
Percentage of Kinderhawk acquired in prior transaction	0.50
Date of first Kinderhawk acquisition	May 21, 2010
Percentage of Eaglehawk Field Services LLC owned by Petrohawk	0.75
Miles of gathering pipe owned by Eaglehawk LLC	280
Miles of condensate line owned by Eaglehawk	140
Carrying value of KinderHawk at time write down	910.2
Fair value of KinderHawk at time of write down	743.0
Value assigned to 25% investment in Eaglehawk	93.4
Subsequent Event Southtex Acquisition
Date of purchase and sale agreement	Oct. 24, 2011
Approximate cash purchase price	155.0
Combined fair value of net assets acquired in KinderHawk acquisition	1,560.9
Tgs Development L P Terminal Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition Cost Of Acquired Entity Purchase Price	74.1
Portion of the purchase price assigned to property, plant and equipment	42.6
Cash consideration given (included in total purchase price)	42.9
Fair value at acquisition date of equity interests issued (included in total purchase price)	23.7
Fair value at acquisition date of liabilities assumed (included in total purchase price)	7.5
Estimated time subsequent to close when liability will be paid (in years)	1Y
Expected amount of petroleum coke to be produced annually by refinery (in tons)	1,000,000
Portion of the purchase price assigned to other intangible assets	31.5
KinderHawk [Member]
Business Acquisition [Line Items]
Acquisition date	2011-07-01
Portion of the purchase price assigned to current assets	35.5
Portion of the purchase price assigned to property, plant and equipment	641.6
Portion of the purchase price allocated to goodwill	94.2
Fair value at acquisition date of liabilities assumed (included in total purchase price)	92.8
Portion of the purchase price assigned to other intangible assets	883.2
Remaining useful life of intangible assets acquired (in years)	20Y
Watco Companies, LLC Acquisition [Member]
Schedule of Equity Method Investments - Acquisitions [Line Items]
Acquisition date	Jan. 03, 2011
Number of Class A preferred shares acquired	50,000
Equity investment purchase price	50.0
Interest rate, per quarter, for cash distributions from the preferred shares (in hundredths)	3.25%
Interest rate applicable to additional profit distributions from the preferred shares (in hundredths)	0.50%
Number of members of the Board of Managers that the Company has the right to appoint	1
Amount reserved for investment in a cash escrow account, included in Restricted Deposits at year end		50.0
Net equity investment at end of period	51.6
Number of short line railroads operated by the investee	22
Length of leased and owned track on which the short line railroads of the investee operate (in miles)	3,500
Deeprock North, LLC Joint Venture [Member]
Schedule of Equity Method Investments - Acquisitions [Line Items]
Acquisition date	Feb. 17, 2011
Equity investment purchase price	15.9
Net equity investment at end of period	22.3
Equity investment percentage of business purchased (in hundredths)	50.00%
Storage capacity of existing crude oil tank farm (in millions of barrels)	1
Expected additional investment for future construction	8.8
Incremental storage capacity to be provided by new storage tanks (in barrels)	750,000
Member interest in joint venture owned by Deeprock Energy Resources, LLC (in hundredths)	12.02%
Member interest in joint venture owned by Mecuria Energy Trading, Inc. (in hundredths)	37.98%
Minimum number of years for which Mecuria will remain the anchor tenant for the joint venture's crude oil capacity	5Y
Number of acres of undeveloped land for which the Company has an option to participate in future expansions	254
Megafleet Towing Co., Inc. Assets Divestiture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from disposal of assets	(4.1)
Gain (loss) on disposal	2.2
Loss resulting from write down of net assets	5.5
Loss, net of tax, resulting from write down of net assets	4.1
Reduction in income tax expense included in gain on sale of assets	1.9
Ownership interest prior to divestiture (in hundredths)	49.00%
Ownership interest of Kirby Corp.	0.51
Date of sale	Feb. 09, 2011
River Consulting, LLC and Devco USA L.L.C. Divestiture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest divested (in hundredths)	51.00%
Number of subsidiaries divested in the disposal transaction	2
Aggregate consideration received	8.1
Consideration received as a note receivable	4.1
Cash proceeds from divestiture of partial interest in formerly consolidated subsidiaries	1.0
Ownership interest retained (in hundredths)	49.00%
Investment in net assets at time of disposal	8.8
Date of sale	Apr. 01, 2011
Tax expense related to gain	1.4
Receivable for settlement of working capital	3.0
Pre tax gain on sale	3.6
Gain on remeasurement to fair value	2.1
Arrow Terminals BV [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from disposal of assets	(13.3)
Pre tax gain on sale	$ 1.3