Fair Value Measurements - Recurring Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Assets:
Derivative assets		$ 9.6
Derivative assets	$ 10.8
Derivative liabilities:
Total derivative liabilities		(52.5)
Fair Value, Measurements, Recurring
Assets:
Derivative assets		11.6
Derivative assets	10.8
Pension plan investments	28.0	27.0
Total recurring assets at fair value	38.8	38.6
Derivative liabilities:
Total derivative liabilities	0.0	(52.5)
Precious metals obligations	(5.6)	(6.9)
Liability awards	(53.6)	(64.2)
Total recurring liabilities at fair value	(59.2)	(123.6)
Fair Value, Measurements, Recurring | Inventory Financing Obligations
Derivative liabilities:
Total derivative liabilities	0.0	(52.5)
Fair Value, Measurements, Recurring | Inventory Financing Obligations
Assets:
Derivative assets	10.8	0.0
Fair Value, Measurements, Recurring | Crack Spread Swaps
Assets:
Derivative assets		11.6
Derivative assets	0.0
Fair Value, Measurements, Recurring | Level 1
Assets:
Derivative assets	0.0	0.0
Pension plan investments	3.8	3.5
Total recurring assets at fair value	3.8	3.5
Derivative liabilities:
Total derivative liabilities	0.0	0.0
Precious metals obligations	(5.6)	(6.9)
Liability awards	(53.6)	(64.2)
Total recurring liabilities at fair value	(59.2)	(71.1)
Fair Value, Measurements, Recurring | Level 1 | Inventory Financing Obligations
Derivative liabilities:
Total derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Level 1 | Inventory Financing Obligations
Assets:
Derivative assets	0.0	0.0
Fair Value, Measurements, Recurring | Level 1 | Crack Spread Swaps
Assets:
Derivative assets	0.0	0.0
Fair Value, Measurements, Recurring | Level 2
Assets:
Derivative assets	0.0	0.0
Pension plan investments	24.2	23.5
Total recurring assets at fair value	24.2	23.5
Derivative liabilities:
Total derivative liabilities	0.0	0.0
Precious metals obligations	0.0	0.0
Liability awards	0.0	0.0
Total recurring liabilities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Level 2 | Inventory Financing Obligations
Derivative liabilities:
Total derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Level 2 | Inventory Financing Obligations
Assets:
Derivative assets	0.0	0.0
Fair Value, Measurements, Recurring | Level 2 | Crack Spread Swaps
Assets:
Derivative assets	0.0	0.0
Fair Value, Measurements, Recurring | Level 3
Assets:
Derivative assets		11.6
Derivative assets	10.8
Pension plan investments	0.0	0.0
Total recurring assets at fair value	10.8	11.6
Derivative liabilities:
Total derivative liabilities	0.0	(52.5)
Precious metals obligations	0.0	0.0
Liability awards	0.0	0.0
Total recurring liabilities at fair value	0.0	(52.5)
Fair Value, Measurements, Recurring | Level 3 | Inventory Financing Obligations
Derivative liabilities:
Total derivative liabilities	0.0	(52.5)
Fair Value, Measurements, Recurring | Level 3 | Inventory Financing Obligations
Assets:
Derivative assets	10.8	0.0
Fair Value, Measurements, Recurring | Level 3 | Crack Spread Swaps
Assets:
Derivative assets		$ 11.6
Derivative assets	$ 0.0