Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 3,511.4	$ 2,852.1	$ 2,087.3
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	1.6	(4.2)	0.9
Available-for-sale investments:
Changes in net unrealized gains (losses) on available-for-sale securities	23.8	(5.7)	25.9
Less: reclassification adjustment for net (gains) losses included in net income	(0.2)	0.0	3.8
Other comprehensive income (loss)	25.2	(9.9)	30.6
Comprehensive income	$ 3,536.6	$ 2,842.2	$ 2,117.9