Accrued Liabilities - Third Parties (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Transportation, project engineering	$ 6.0	$ 6.1
Property taxes	4.2	2.2
Other accrued liabilities	2.5	3.9
Accrued liabilities - third parties	12.7	12.2	[1]
Environmental accrual	0.0	6.3
Total noncurrent accrued liabilities - third parties	$ 0.0	$ 6.3	[1]

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