Description of the Business and Summary of Significant Accounting Policies - Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 118.3	$ 118.4
Mobile
Disaggregation of Revenue [Line Items]
Total revenue	101.2	96.9
Web
Disaggregation of Revenue [Line Items]
Total revenue	17.1	21.5
North America
Disaggregation of Revenue [Line Items]
Total revenue	108.0	108.4
International
Disaggregation of Revenue [Line Items]
Total revenue	$ 10.3	$ 10.0