Significant Accounting Policies - Equity Instruments and Investments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Equity Instruments and Investments
Equity instruments with readily determinable fair value	$ 102.5	$ 73.0
Equity instruments without readily determinable fair values	238.5	236.2
Debt securities of our captive insurance companies	$ 51.0	$ 52.3
Debt Securities | Securities in captive insurance subsidiary portfolio | Maximum
Equity Instruments and Investments
Short-term investment maturity period	1 year
Investment maturity period	10 years