Goodwill and Intangible Assets - Carrying Value of Goodwill (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 108.6
Acquisition	134.3
Ending balance	242.9
DWS
Goodwill [Roll Forward]
Beginning balance	0.0
Acquisition	134.3
Ending balance	134.3
C&I
Goodwill [Roll Forward]
Beginning balance	0.0
Acquisition	0.0
Ending balance	0.0
ECS
Goodwill [Roll Forward]
Beginning balance	98.3
Acquisition	0.0
Ending balance	98.3
Other
Goodwill [Roll Forward]
Beginning balance	10.3
Acquisition	0.0
Ending balance	$ 10.3