Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 86.8	$ 250.0	$ 408.5	$ 740.7
Other comprehensive loss, net of tax:
Unrealized loss on securities, net of tax	(1.2)	(0.2)	(3.6)	(0.9)
Other comprehensive loss	(1.2)	(0.2)	(3.6)	(0.9)
Comprehensive income	$ 85.6	$ 249.8	$ 404.9	$ 739.8