Other Assets and Liabilities Other Current Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Other Assets, Noncurrent [Line Items]
Total	$ 135.7	$ 129.9
Other Current Assets
Other Assets, Noncurrent [Line Items]
Prepaid expenses	15.8	17.6
Short-term derivative assets	61.9	15.9
Income and other tax receivables	24.3	74.9
RINs Obligation Surplus	0.0	1.1
Commodity investments	15.6	0.0
Other	18.1	20.4
Total	$ 135.7	$ 129.9