Derivative Instruments - Derivatives Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses)	$ 77.9	$ 17.5
Not Designated as Hedging Instrument | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on economic hedges	52.0	(27.1)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments that have matured but not cash settled	37.6	(5.6)
Not Designated as Hedging Instrument | Commodity contracts | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivatives not designated as hedging instruments	77.2	38.9
Not Designated as Hedging Instrument | Commodity contracts | Other Operating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivatives not designated as hedging instruments	0.0	(2.3)
Designated as Hedging Instrument | Commodity contracts | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Realized gains (losses) reclassified out of accumulated other comprehensive income and into cost of materials and other on commodity derivatives designated as cash flow hedging instruments	$ 0.7	$ (19.1)