Fair Value - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on derivative	$ (0.2)	$ 1.5	$ (1.6)	$ 2.2
Cash flow hedge gain (loss) to be reclassified within 12 months			(2.7)
Not designated as hedging instrument | Natural gas forward contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on derivative	0.1	0.7	1.1	0.0
Gain on the settlement of contracts	$ 0.1	$ 1.2	$ 1.5	$ 3.7