Restructuring - Changes in Restructuring Liability (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Restructuring Reserve [Roll Forward]
Restructuring liability, Beginning Balance	$ 42.3
Adoption of New Lease Accounting Standard	(10.9)
Cost incurred and adjustments	29.4
Cash payments and adjustments	(29.5)
Restructuring liability, Ending Balance	31.3
Employee Termination Costs
Restructuring Reserve [Roll Forward]
Restructuring liability, Beginning Balance	29.9
Adoption of New Lease Accounting Standard	0.0
Cost incurred and adjustments	25.1
Cash payments and adjustments	(26.5)
Restructuring liability, Ending Balance	28.5
Cumulative expense incurred to date	58.0
Contract Termination Costs
Restructuring Reserve [Roll Forward]
Restructuring liability, Beginning Balance	12.4
Adoption of New Lease Accounting Standard	(10.9)
Cost incurred and adjustments	4.3
Cash payments and adjustments	(3.0)
Restructuring liability, Ending Balance	2.8
Cumulative expense incurred to date	$ 49.0