Restructuring Charge - Narrative (Details) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
		Feb. 07, 2019 USD ($)	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($) employee	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($) employee
Restructuring and Related Activities [Abstract]
Restructuring charge	[1]	$ 0.1	$ 4.9	$ 8.2	$ 16.2	$ 44.1
Severance costs		$ 0.1	$ 2.3	$ 5.0	$ 8.5	$ 32.8
Number of employees impacted | employee			45	75	145	455
Contract termination, write-down of right-of-use assets and other exit costs			$ 2.6	$ 3.2	$ 7.7	$ 11.3

[1] See Note 1 "Basis of Presentation" for further discussion.