Revenue - Schedule of Revenues Disaggregation by Contract Type (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
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	(8.7)	(17.9)	(26.4)	(26.4)
Transferred at Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenues	67.4	105.9	155.8	170.4
Transferred over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenues	487.0	1,032.8	1,404.0	1,366.3
Network [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	303.8	664.2	969.6	995.7
Network [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	6.5	13.1	19.7	21.6
Network [Member] | Transferred at Point in Time [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	8.0	15.8	27.9	31.7
Network [Member] | Transferred over Time [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	289.3	635.3	922.0	942.4
IT Services and Hardware [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	259.3	492.4	616.6	567.4
IT Services and Hardware [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	2.2	4.8	6.7	4.8
IT Services and Hardware [Member] | Transferred at Point in Time [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	59.4	90.1	127.9	138.7
IT Services and Hardware [Member] | Transferred over Time [Member] | Operating Segments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 197.7	$ 397.5	$ 482.0	$ 423.9