Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 813.8	$ 637.7
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	0.7	(1.4)
Available-for-sale investments:
Change in net unrealized gains (losses) on available-for-sale securities	10.6	(7.2)
Other comprehensive income (loss)	11.3	(8.6)
Comprehensive income	$ 825.1	$ 629.1