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Goodwill and Other Intangible Assets - Intangible Assets by Asset Type (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Intangible Assets [Line Items] |  |
Gross Carrying Amount | $ 2,844.5 | $ 2,803.0
Accumulated Amortization | (2,399.4) | (2,208.9)
Net Carrying Amount | 445.1 | 594.1
Customer relationships and contracts |  |
Intangible Assets [Line Items] |  |
Gross Carrying Amount | 2,131.5 | 2,111.2
Accumulated Amortization | (1,927.9) | (1,786.4)
Net Carrying Amount | $ 203.6 | $ 324.8
Trade name |  |
Intangible Assets [Line Items] |  |
Useful Life (Years) | 20 years | 20 years
Gross Carrying Amount | $ 422.8 | $ 422.8
Accumulated Amortization | (280.1) | (259.0)
Net Carrying Amount | 142.7 | 163.8
Internally developed software |  |
Intangible Assets [Line Items] |  |
Gross Carrying Amount | 280.6 | 263.5
Accumulated Amortization | (186.0) | (160.0)
Net Carrying Amount | 94.6 | 103.5
Other |  |
Intangible Assets [Line Items] |  |
Gross Carrying Amount | 9.6 | 5.5
Accumulated Amortization | (5.4) | (3.5)
Net Carrying Amount | $ 4.2 | $ 2.0
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

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