Fair Value - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months	$ (1.9)
Gain (loss) on derivative	$ 0.6	$ (2.2)	$ 0.2
Measurement Input, Long-term Revenue Growth Rate | Valuation Technique, Option Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative liability, unobservable inputs	0.07	0.07
Measurement Input, Price Volatility | Valuation Technique, Option Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative liability, unobservable inputs	0.20	0.20
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)	$ (0.8)
Gain on the settlement of contracts	$ 4.5	$ 3.6