Other Comprehensive Income (Loss) - Summary of Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 591.9	$ 567.0	$ 555.2
Other comprehensive income (loss)	1.5	2.7	(5.7)
Ending balance	631.9	591.9	567.0
Defined benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0.2	0.4	0.6
Other comprehensive income (loss)	(0.4)	(0.2)	(0.2)
Ending balance	(0.2)	0.2	0.4
Foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5.3)	(8.2)	(2.7)
Other comprehensive income (loss)	1.9	2.9	(5.5)
Ending balance	(3.4)	(5.3)	(8.2)
Other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5.1)	(7.8)	(2.1)
Ending balance	$ (3.6)	$ (5.1)	$ (7.8)