CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 11.6	$ 0.8	$ 23.9	$ 6.6
Other comprehensive income (loss), net of tax:
Currency translation adjustment	3.3	(1.8)	0.5	(3.0)
Unrealized (loss) gain on available-for-sale debt securities	(0.3)	0.0	0.1	1.3
Total other comprehensive income (loss), net of tax	3.0	(1.8)	0.6	(1.7)
Comprehensive income (loss)	$ 14.6	$ (1.0)	$ 24.5	$ 4.9