Equity Method Investments - Schedule of Equity Investments in Affiliates Balance Affected (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013	[2]
Schedule Of Equity Method Investments [Line Items]
Distributions received		$ 76.3		$ 8.3
Income from equity investments		70.1	[1]	6.7	[2]	$ 0.0
Return of investment	[3]	6.8	[1]	2.1	[2]
Income in excess of distributions	[4]	(0.6)	[1]	(0.5)	[2]
Mars
Schedule Of Equity Method Investments [Line Items]
Distributions received		34.9		5.5
Income from equity investments		33.2		3.4
Return of investment	[3]	1.7		2.1
Bengal
Schedule Of Equity Method Investments [Line Items]
Distributions received		20.2		2.8
Income from equity investments		20.8		3.3
Income in excess of distributions	[4]	(0.6)		$ (0.5)
Poseidon
Schedule Of Equity Method Investments [Line Items]
Distributions received		21.2
Income from equity investments		16.1
Return of investment	[3]	$ 5.1

[1] The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations from January 1, 2015 through September 30, 2015.

[2] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.

[3] Distributions received in excess of our income from equity investments is shown as a return of investment in our consolidated statements of cash flows.

[4] Income from equity investments in excess of distributions is shown as a reduction to cash flows from operating activities in our consolidated statements of cash flows.