Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Deferred gains and other long-term liabilities
Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 865.2	$ 1,346.4
Restricted cash	119.4	119.4
Short-term investment securities	112.5	107.1
Total assets	1,097.1	1,572.9
Derivative liability	11.1
Total liabilities	11.1	29.2
Recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	865.2	1,346.4
Restricted cash	119.4	119.4
Short-term investment securities	112.5	107.1
Total assets	1,097.1	1,572.9
Derivative liability	0.0
Total liabilities	0.0	0.0
Recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Short-term investment securities	0.0	0.0
Total assets	0.0	0.0
Derivative liability	11.1
Total liabilities	11.1	29.2
Recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Short-term investment securities	0.0	0.0
Total assets	0.0	0.0
Derivative liability	0.0
Total liabilities	$ 0.0	$ 0.0