Equity Method Investments - Schedule of Equity Investments in Affiliates Balance Affected (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015		Dec. 01, 2017	Oct. 17, 2017	Jul. 01, 2015
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 198.3	$ 158.0		$ 112.9
Income from equity method investments	186.6	138.1	[1]	104.7	[1]
Purchase price adjustment	0.3	0.0	[2]	0.0	[2]
Mars
Schedule of Equity Method Investments [Line Items]
Distributions received	125.9	88.3		62.8
Income from equity method investments	121.8	$ 79.8		59.4
Purchase price adjustment	$ 0.0
Ownership interest (in percentage)	71.50%	71.50%
Bengal
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 19.0	$ 19.6		20.2
Income from equity method investments	22.6	$ 20.2		20.8
Purchase price adjustment	$ 0.0
Ownership interest (in percentage)	50.00%	50.00%
Permian Basin
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 1.4	$ 0.0		0.0
Income from equity method investments	0.9	$ 0.0		0.0
Purchase price adjustment	$ (0.1)
Ownership interest (in percentage)	50.00%	0.00%
LOCAP
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 7.9	$ 8.2		8.7
Income from equity method investments	10.7	$ 8.4		8.4
Purchase price adjustment	$ 0.0
Ownership interest (in percentage)	41.48%	41.48%
Poseidon
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 38.4	$ 41.9		21.2
Income from equity method investments	27.4	$ 29.7		16.1
Purchase price adjustment	$ 0.0
Ownership interest (in percentage)	36.00%	36.00%
Proteus
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 2.9	$ 0.0		0.0
Income from equity method investments	1.5	$ 0.0		0.0
Purchase price adjustment	$ 0.3
Ownership interest (in percentage)	10.00%	10.00%
Endymion
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 2.8	$ 0.0		0.0
Income from equity method investments	1.7	$ 0.0		$ 0.0
Purchase price adjustment	$ 0.1
Ownership interest (in percentage)	10.00%	10.00%
Proteus and Endymion
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	$ 0.1
Permian Basin
Schedule of Equity Method Investments [Line Items]
Voting interest acquired							50.00%
Ownership interest (in percentage)	50.00%
LOCAP
Schedule of Equity Method Investments [Line Items]
Voting interest acquired						41.48%
July 2015 Acquisition
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)								36.00%

[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.