Other Assets and Liabilities - Other Current Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Other Assets and Liabilities [Abstract]
Short-term derivative assets (see Note 9)	$ 33.0	$ 30.2
Income and other tax receivable	181.1	61.9
RINs assets	231.1	14.5
Right to receive crude oil barrels (see Note 10)	36.6	0.0
Prepaid expenses	19.2	21.9
Biodiesel tax credit (see Note 2)	3.2	97.5
Environmental Credits Obligation surplus (see Note 10)	7.3	16.8
Commodity investments	1.0	12.1
Other	3.4	13.8
Total	$ 515.9	$ 268.7