Description of the Business and Summary of Significant Accounting Policies - Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 165.6	$ 118.1	$ 283.9	$ 236.5
Mobile
Disaggregation of Revenue [Line Items]
Revenue	144.3	98.2	245.5	195.1
Web
Disaggregation of Revenue [Line Items]
Revenue	21.3	19.9	38.4	41.4
North America
Disaggregation of Revenue [Line Items]
Revenue	152.6	111.1	260.6	219.5
International
Disaggregation of Revenue [Line Items]
Revenue	$ 13.0	$ 7.0	$ 23.3	$ 17.0

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration