Other Assets and Liabilities - Other Current Assets (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Other Assets and Liabilities [Line Items]
Total	$ 107.7	$ 129.9
Other current assets
Schedule of Other Assets and Liabilities [Line Items]
Prepaid expenses	13.5	17.6
Short-term derivative assets (see Note 16)	39.9	15.9
Income and other tax receivables	15.5	75.7
RINs Obligation surplus (see Note 15)	4.1	1.1
Commodity investments	18.1	0.0
Total	$ 16.6	$ 19.6