Fair Value Measurements - Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Financial instruments
Preferred stock of subsidiary	$ 30.4	$ 30.4
Long-term debt, including current portion	15,464.2	13,563.4
Finance lease obligation	183.2	129.7
Carrying amount
Financial instruments
Preferred stock of subsidiary	30.4	30.4
Long-term debt, including current portion	15,464.2	13,563.4
Finance lease obligation	183.2	129.7
Fair value
Financial instruments
Preferred stock of subsidiary	22.7	30.3
Long-term debt, including current portion	$ 13,921.3	$ 14,819.4