Other Intangible Assets - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,304.7	$ 1,225.2
Accumulated amortization	(691.5)	(532.9)
Net carrying amount	613.2	692.3
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,282.2	1,206.0
Accumulated amortization	(680.6)	(525.9)
Net carrying amount	601.6	680.1
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	22.5	19.2
Accumulated amortization	(10.9)	(7.0)
Net carrying amount	$ 11.6	$ 12.2