Goodwill and Intangible Assets - Schedule of Goodwill (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)
Goodwill [Line Items]
Goodwill, beginning balance	$ 646.3
Adjustments to prior year Merger	4.7
Acquisition of Agile	35.3
Adjustments to postretirement and other benefit obligations (Note 8)	35.0
Currency translations	(2.3)
Goodwill, ending balance	719.0
IT Services and Hardware [Member] | Operating Segments
Goodwill [Line Items]
Goodwill, beginning balance	157.4
Adjustments to prior year Merger	2.5
Acquisition of Agile	0.0
Adjustments to postretirement and other benefit obligations (Note 8)	19.6
Currency translations	(2.3)
Goodwill, ending balance	177.2
Network [Member] | Operating Segments
Goodwill [Line Items]
Goodwill, beginning balance	488.9
Adjustments to prior year Merger	2.2
Acquisition of Agile	35.3
Adjustments to postretirement and other benefit obligations (Note 8)	15.4
Currency translations	0.0
Goodwill, ending balance	$ 541.8