Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 64.3	$ 99.5
Other comprehensive gain (loss), net of tax:
Unrealized gain (loss) on securities, net of tax	(0.2)	0.8
Other comprehensive gain (loss)	(0.2)	0.8
Comprehensive income	$ 64.1	$ 100.3