Acquisitions and Divestiture - 2017 Acquisitions and Divestiture - Narrative (Details) - USD ($) $ in Millions							1 Months Ended		3 Months Ended	8 Months Ended	12 Months Ended
		Dec. 01, 2017	Oct. 17, 2017	Sep. 15, 2017	May 10, 2017	Apr. 28, 2017	Dec. 31, 2017	May 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]	Oct. 03, 2016	Aug. 09, 2016
Business Acquisition [Line Items]
Divestiture cash consideration											$ 0.8	$ 0.0		$ 0.0
Excess proceeds from divestiture from Parent	[2]										$ 20.2
Triton West LLC (“Triton”)
Business Acquisition [Line Items]
Voting interest acquired		100.00%
LOCAP LLC (“LOCAP”)
Business Acquisition [Line Items]
Voting interest acquired		41.48%
Mars Oil Pipeline Company LLC (“Mars”)
Business Acquisition [Line Items]
Voting interest acquired		22.90%														20.00%
Odyssey Pipeline L.L.C. (“Odyssey”)
Business Acquisition [Line Items]
Voting interest acquired		22.00%
Explorer
Business Acquisition [Line Items]
Voting interest acquired		10.00%															2.62%
December 2017 Acquisition
Business Acquisition [Line Items]
Consideration transferred		$ 825.0
Transaction costs		0.6
Contribution in excess of book value of net assets acquired		$ 605.2
Revenue related to acquisition							$ 7.7
Net earnings related to acquisition							$ 18.8
Crestwood Permian Basin LLC (“Permian Basin”)
Business Acquisition [Line Items]
Voting interest acquired			50.00%
Consideration transferred			$ 49.9
May 2017 Acquisition
Business Acquisition [Line Items]
Voting interest acquired					100.00%
Consideration transferred					$ 630.0
Transaction costs					0.8
Contribution in excess of book value of net assets acquired					429.3
Revenue related to acquisition										$ 63.8
Net earnings related to acquisition										$ 29.3
Consideration, cash on hand					50.0
Shutdown period								2 years
Five Year Fixed Facility
Business Acquisition [Line Items]
Debt instrument term											5 years
Shell Treasury Center West Inc | Five Year Revolver
Business Acquisition [Line Items]
Debt instrument term				5 years					5 years		5 years
Revolving Credit Facility | Shell Treasury Center West Inc | Five Year Revolver | May 2017 Acquisition
Business Acquisition [Line Items]
Consideration, funded with borrowings					73.1
Line of Credit | Five Year Fixed Facility | May 2017 Acquisition
Business Acquisition [Line Items]
Consideration, funded with borrowings					506.9
Line of Credit | Shell Treasury Center West Inc | Five Year Fixed Facility | May 2017 Acquisition
Business Acquisition [Line Items]
Consideration, funded with borrowings					$ 506.9
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] | Zydeco
Business Acquisition [Line Items]
Divestiture cash consideration						$ 21.0
Book value of net assets divested						0.8
Excess proceeds from divestiture from Parent						20.2
Shell Pipeline Company L P | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] | Zydeco
Business Acquisition [Line Items]
Divestiture cash consideration						$ 19.4

[1] The financial information presented has been retrospectively adjusted for acquisitions of businesses under common control.

[2] The financial information presented has been retrospectively adjusted for acquisitions of businesses under common control.