Revenue - Schedule of Revenues Disaggregation by Contract Type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenues	$ 439.5	$ 414.2	$ 875.3	$ 824.1
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	(6.5)	(6.7)	(13.0)	(13.4)
Network [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	247.0	241.0	490.5	483.8
Network [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	4.8	4.9	9.7	9.7
IT Services and Hardware [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	199.0	179.9	397.8	353.7
IT Services and Hardware [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	1.7	1.8	3.3	3.7
Transferred at Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenues	44.2	37.4	90.1	76.7
Transferred at Point in Time [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Transferred at Point in Time [Member] | Network [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	6.1	5.8	13.5	11.7
Transferred at Point in Time [Member] | IT Services and Hardware [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	38.1	31.6	76.6	65.0
Transferred over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenues	395.3	376.8	785.2	747.4
Transferred over Time [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Transferred over Time [Member] | Network [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	236.1	230.3	467.3	462.4
Transferred over Time [Member] | IT Services and Hardware [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	$ 159.2	$ 146.5	$ 317.9	$ 285.0