Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Footnotes (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Goodwill
Acquired Finite-Lived Intangible Assets [Line Items]
Foreign currency translation	$ (1.2)	$ 0.0
NSM Holding Co LLC | Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Foreign currency translation		$ 0.4	$ (0.7)
NSM Holding Co LLC | Goodwill
Acquired Finite-Lived Intangible Assets [Line Items]
Foreign currency translation	$ (0.1)		(2.2)
Buzzmove | Goodwill
Acquired Finite-Lived Intangible Assets [Line Items]
Foreign currency translation			$ (0.3)