Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 70.8	$ 86.8	$ 192.5	$ 408.5
Other comprehensive loss, net of tax:
Unrealized loss on securities, net of tax	(0.2)	(1.2)	0.0	(3.6)
Other comprehensive loss	(0.2)	(1.2)	0.0	(3.6)
Comprehensive income	$ 70.6	$ 85.6	$ 192.5	$ 404.9