Investments - Schedule of Realized and Unrealized Gains and Losses on Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Unrealized gains on equity securities held as of the end of the period	$ 2.6	$ 2.9	$ 25.8
Realized gains (losses) for equity securities sold during the period	0.3	0.7	(1.1)
Total gains recognized in other income , net	$ 2.9	$ 3.6	$ 24.7