Fair Value Measurements - Commodity and Foreign Currency Contracts (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Offsetting Assets [Line Items]
Gross Amounts Recognized	$ 1,428.0	$ 261.1
Gross Amounts Offset	1,076.6	131.1
Net Amounts Presented	351.5	130.0
Cash Collateral	28.4	0.0
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	323.1	130.0
Offsetting Liabilities [Line Items]
Gross Amounts Recognized	1,294.6	266.6
Gross Amounts Offset	1,076.6	131.1
Net Amounts Presented	218.1	135.5
Cash Collateral	76.7	29.3
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	141.4	106.3
Commodity contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	1,400.9	259.0
Gross Amounts Offset	1,069.8	130.0
Net Amounts Presented	331.2	129.0
Cash Collateral	28.4	0.0
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	302.8	129.0
Offsetting Liabilities [Line Items]
Gross Amounts Recognized	1,282.8	255.0
Gross Amounts Offset	1,069.8	130.0
Net Amounts Presented	213.1	125.0
Cash Collateral	76.7	29.3
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	136.4	95.7
Interest rate contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	0.0
Gross Amounts Offset	0.0
Net Amounts Presented	0.0
Cash Collateral	0.0
Gross Amounts without Right of Offset	0.0
Net Amounts	0.0
Offsetting Liabilities [Line Items]
Gross Amounts Recognized	2.0
Gross Amounts Offset	0.0
Net Amounts Presented	2.0
Cash Collateral	0.0
Gross Amounts without Right of Offset	0.0
Net Amounts	2.0
Foreign currency contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	27.1	2.0
Gross Amounts Offset	6.8	1.0
Net Amounts Presented	20.3	1.0
Cash Collateral	0.0	0.0
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	20.3	1.0
Offsetting Liabilities [Line Items]
Gross Amounts Recognized	9.8	11.6
Gross Amounts Offset	6.8	1.0
Net Amounts Presented	3.0	10.5
Cash Collateral	0.0	0.0
Gross Amounts without Right of Offset	0.0	0.0
Net Amounts	$ 3.0	$ 10.5