Construction Reserve Funds - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) ExtensionPeriod	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Restricted Cash And Investments [Abstract]
Construction reserve funds commitment period	3 years
Number of extension period | ExtensionPeriod	2
Construction reserve funds extension period	1 year
Short-term construction reserve funds	$ 0.0	$ 4.2
Construction reserve fund withdrawals	$ 4.2	$ 9.1	$ 15.2