Equity Method Investments - Schedule of Equity Investments in Affiliates Balance Affected (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Schedule of Equity Method Investments [Line Items]
Distributions Received	$ 38.9		$ 31.5		$ 82.8		$ 57.8
Income from equity investments	37.2	[1]	25.6	[2]	75.9	[1]	48.8	[2]
Purchase price adjustment	0.0				0.4	[3]	0.0	[4]
Bengal
Schedule of Equity Method Investments [Line Items]
Distributions Received	4.6		7.1		9.3		13.4
Income from equity investments	5.4		5.3		10.7		10.7
Purchase price adjustment	0.0				0.0
Odyssey
Schedule of Equity Method Investments [Line Items]
Distributions Received	4.5				8.7
Income from equity investments	4.4				8.7
Purchase price adjustment	0.0				0.0
Mars
Schedule of Equity Method Investments [Line Items]
Distributions Received	19.0		13.1		42.3		23.0
Income from equity investments	20.2		12.2		41.7		23.1
Purchase price adjustment	0.0				0.0
Poseidon
Schedule of Equity Method Investments [Line Items]
Distributions Received	9.2		11.3		19.3		21.4
Income from equity investments	6.4		$ 8.1		13.2		$ 15.0
Purchase price adjustment	0.0				0.0
Proteus
Schedule of Equity Method Investments [Line Items]
Distributions Received	0.8				1.7
Income from equity investments	0.4				0.8
Purchase price adjustment	0.0				0.3
Endymion
Schedule of Equity Method Investments [Line Items]
Distributions Received	0.8				1.5
Income from equity investments	0.4				0.8
Purchase price adjustment	$ 0.0				$ 0.1

[1] The 2017 financial information reflects adjustments for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations from January 1, 2017 through May 9, 2017.

[2] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.

[3] The 2017 financial information reflects adjustments for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations from January 1, 2017 through May 9, 2017.

[4] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.