Goodwill and Other Intangible Assets - Intangible Assets by Asset Type (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,803.0	$ 2,702.6
Accumulated Amortization	(2,208.9)	(1,990.4)
Net Carrying Amount	594.1	712.2
Customer relationships and contracts
Intangible Assets [Line Items]
Gross Carrying Amount	2,111.2	2,071.0
Accumulated Amortization	(1,786.4)	(1,625.5)
Net Carrying Amount	$ 324.8	$ 445.5
Trade name
Intangible Assets [Line Items]
Useful Life (Years)	20 years	20 years
Gross Carrying Amount	$ 422.8	$ 422.1
Accumulated Amortization	(259.0)	(237.3)
Net Carrying Amount	163.8	184.8
Internally developed software
Intangible Assets [Line Items]
Gross Carrying Amount	263.5	205.8
Accumulated Amortization	(160.0)	(125.4)
Net Carrying Amount	103.5	80.4
Other
Intangible Assets [Line Items]
Gross Carrying Amount	5.5	3.7
Accumulated Amortization	(3.5)	(2.2)
Net Carrying Amount	$ 2.0	$ 1.5
Minimum | Customer relationships and contracts
Intangible Assets [Line Items]
Useful Life (Years)	3 years	3 years
Minimum | Internally developed software
Intangible Assets [Line Items]
Useful Life (Years)	3 years	3 years
Minimum | Other
Intangible Assets [Line Items]
Useful Life (Years)	1 year	1 year
Maximum | Customer relationships and contracts
Intangible Assets [Line Items]
Useful Life (Years)	14 years	14 years
Maximum | Internally developed software
Intangible Assets [Line Items]
Useful Life (Years)	5 years	5 years
Maximum | Other
Intangible Assets [Line Items]
Useful Life (Years)	10 years	10 years