Business Segment Information - Selected Financial Data for the Company's Business Segment Information (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
Segment Reporting Information [Line Items]
Revenue	$ 554.4	$ 1,138.7	$ 1,559.8	$ 1,536.7
Operating (loss) income	(9.1)	27.7	66.0	73.1
Expenditures for long-lived assets	1,749.4	215.7	230.0	223.8
Depreciation and amortization	144.6	194.9	293.4	304.9
Assets	4,198.8		2,668.6
Operating Segments [Member] | Network [Member]
Segment Reporting Information [Line Items]
Revenue	303.8	664.2	969.6	995.7
Operating (loss) income	(6.3)	78.3	99.7	105.5
Expenditures for long-lived assets	114.8	199.8	206.4	201.3
Depreciation and amortization	113.0	166.9	252.7	255.8
Assets	2,949.2		1,803.3
Operating Segments [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	259.3	492.4	616.6	567.4
Operating (loss) income	4.0	25.2	24.6	2.6
Expenditures for long-lived assets	13.9	15.9	23.5	22.4
Depreciation and amortization	31.4	27.9	40.6	48.9
Assets	842.0		477.2
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(8.7)	(17.9)	(26.4)	(26.4)
Intersegment Eliminations [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Revenue	8.7	17.9	26.4	26.4
Intersegment Eliminations [Member] | Network [Member]
Segment Reporting Information [Line Items]
Revenue	6.5	13.1	19.7	21.6
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	2.2	4.8	6.7	4.8
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating (loss) income	(6.8)	(75.8)	(58.3)	(35.0)
Expenditures for long-lived assets	1,620.7		0.1	0.1
Depreciation and amortization	0.2	$ 0.1	0.1	$ 0.2
Corporate and Elimination [Member]
Segment Reporting Information [Line Items]
Assets	$ 407.6		$ 388.1