Revenue - Schedule of Revenues Disaggregation by Product and Service Lines (Details) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2021	Sep. 07, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Revenues	$ 554.4	$ 1,138.7	$ 1,559.8	$ 1,536.7
Operating Segments [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	303.8	664.2	969.6	995.7
Operating Segments [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	259.3	492.4	616.6	567.4
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	(8.7)	(17.9)	(26.4)	(26.4)
Intersegment Eliminations [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	6.5	13.1	19.7	21.6
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	2.2	4.8	6.7	4.8
Data [Member] | Operating Segments [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	156.2	334.6	479.4	475.0
Video [Member] | Operating Segments [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	60.4	131.8	193.8	203.0
Voice [Member] | Operating Segments [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	76.4	177.3	262.8	284.9
Other [Member] | Operating Segments [Member] | Network [Member]
Disaggregation Of Revenue [Line Items]
Revenues	10.8	20.5	33.6	32.8
Consulting [Member] | Operating Segments [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	105.5	193.6	196.0	152.6
Cloud [Member] | Operating Segments [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	31.9	66.4	86.2	92.1
Communications [Member] | Operating Segments [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	68.5	149.1	215.0	198.7
Infrastructure Solutions [Member] | Operating Segments [Member] | IT Services and Hardware [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 53.4	$ 83.3	$ 119.4	$ 124.0