Restructuring Charges - Roll-forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Charges/ (Benefits)	$ 35.3	$ 7.3	$ 65.6
2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	35.3
Cash Payments	(33.5)
Other	(2.2)
Restructuring liability, ending balance	0.7	1.1
2019 Restructuring Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	21.5
Cash Payments	(21.9)
Other	0.0
Restructuring liability, ending balance	0.7	1.1
2019 Restructuring Plan | Facility consolidations
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0.0
Charges/ (Benefits)	2.1
Cash Payments	(0.1)
Other	(2.0)
Restructuring liability, ending balance	0.0	0.0
2019 Restructuring Plan | Contract terminations
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0.0
Charges/ (Benefits)	11.7
Cash Payments	(11.5)
Other	(0.2)
Restructuring liability, ending balance	$ 0.0	$ 0.0