Fair Value - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on derivative	$ (0.9)	$ 0.4	$ (1.5)	$ 0.7
Cash flow hedge gain (loss) to be reclassified within 12 months			(1.7)
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	0.7	(0.1)	0.9	(0.7)
Gain on the settlement of contracts	$ 0.7	$ 1.5	$ 1.4	$ 2.5