Revenue - Schedule of Revenues Disaggregation by Product and Service Lines (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation Of Revenue [Line Items]
Revenues	$ 435.8	$ 409.9
Operating Segments | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	243.5	242.8
Operating Segments | Network [Member] | Data [Member]
Disaggregation Of Revenue [Line Items]
Revenues	126.1	121.3
Operating Segments | Network [Member] | Video [Member]
Disaggregation Of Revenue [Line Items]
Revenues	48.6	48.6
Operating Segments | Network [Member] | Voice [Member]
Disaggregation Of Revenue [Line Items]
Revenues	59.3	65.9
Operating Segments | Network [Member] | Other [Member]
Disaggregation Of Revenue [Line Items]
Revenues	9.5	7.0
Operating Segments | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	198.8	173.8
Operating Segments | IT Services and Hardware [Member] | Consulting
Disaggregation Of Revenue [Line Items]
Revenues	83.4	65.5
Operating Segments | IT Services and Hardware [Member] | Cloud
Disaggregation Of Revenue [Line Items]
Revenues	24.6	23.4
Operating Segments | IT Services and Hardware [Member] | Communications
Disaggregation Of Revenue [Line Items]
Revenues	54.9	54.0
Operating Segments | IT Services and Hardware [Member] | Infrastructure Solutions
Disaggregation Of Revenue [Line Items]
Revenues	35.9	30.9
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	(6.5)	(6.7)
Intersegment Eliminations [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	4.9	4.8
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 1.6	$ 1.9