Crude Oil Supply and Inventory Purchase Agreement - Recurring Cash Fee Paid (Details) - Interest expense - J. Aron - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	$ 3.3	$ 6.9	$ 13.3	$ 20.5
El Dorado Refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	1.5	2.9	7.4	8.5
Krotz Spring Refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	1.1	2.5	3.1	7.6
Big Spring refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	$ 0.7	$ 1.5	$ 2.8	$ 4.4