Equity Method Investments - Schedule of Equity Investments in Affiliates Balance Affected (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 26.3	$ 15.7
Income from equity investments	23.2	12.5	[1]
Return of investment	4.1	3.2	[2]
Income in excess of distributions	(1.0)	0.0	[2]
Mars
Schedule of Equity Method Investments [Line Items]
Distributions received	9.9	8.6
Income from equity investments	10.9	7.4
Return of investment	0.0	1.2
Income in excess of distributions	(1.0)
Amortization	0.2	0.4
Bengal
Schedule of Equity Method Investments [Line Items]
Distributions received	6.3	7.1
Income from equity investments	5.4	5.1
Return of investment	0.9	2.0
Income in excess of distributions	0.0
Amortization	(0.1)	$ (0.1)
Poseidon
Schedule of Equity Method Investments [Line Items]
Distributions received	10.1
Income from equity investments	6.9
Return of investment	3.2
Income in excess of distributions	0.0
Amortization	$ 0.2

[1] (1) The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.

[2] (1) The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.