Business Segment Information - Selected Financial Data for the Company's Business Segment Information (Details) - USD ($) $ in Millions		1 Months Ended	2 Months Ended	3 Months Ended	8 Months Ended	9 Months Ended
		Sep. 30, 2021	Sep. 07, 2021	Sep. 30, 2020	Sep. 07, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues		$ 111.4	$ 314.6	$ 389.5	$ 1,138.7	$ 1,149.5
Operating (loss) income		(1.4)	(35.3)	24.7	27.7	32.2
Expenditures for long-lived assets	[1]	1,657.4	96.0	61.5	215.7	160.9
Depreciation and amortization		30.2	52.1	71.9	194.9	220.8
Assets		4,090.4					$ 2,668.6
Operating Segments [Member] | Entertainment and Communications [Member]
Segment Reporting Information [Line Items]
Revenues		61.7	180.4	241.0	664.2	724.5
Operating (loss) income		(2.3)	18.9	27.2	78.3	69.8
Expenditures for long-lived assets	[1]	33.4	92.0	57.6	199.8	144.2
Depreciation and amortization		24.3	44.5	61.6	166.9	190.0
Assets		2,885.3					1,803.3
Operating Segments [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenues		52.0	138.7	155.2	492.4	444.5
Operating (loss) income		1.7	9.0	4.6	25.2	11.5
Expenditures for long-lived assets	[1]	3.3	4.0	3.9	15.9	16.7
Depreciation and amortization		5.8	7.6	10.2	27.9	30.7
Assets		844.9					477.2
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues		(2.3)	(4.5)	(6.7)	(17.9)	(19.5)
Intersegment Elimination [Member] | Entertainment and Communications [Member]
Segment Reporting Information [Line Items]
Revenues		1.6	3.4	4.9	13.1	14.8
Intersegment Elimination [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenues		0.7	1.1	1.8	4.8	4.7
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating (loss) income		(0.8)	(63.2)	(7.1)	(75.8)	(49.1)
Expenditures for long-lived assets	[1]	1,620.7	0.0	0.0	0.0	0.0
Depreciation and amortization		0.1	0.0	0.1	0.1	0.1
Corporate and Elimination [Member]
Segment Reporting Information [Line Items]
Assets		360.2					$ 388.1
Sales [Member] | Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues		$ 2.3	$ 4.5	$ 6.7	$ 17.9	$ 19.5

[1] Includes cost of acquisitions in the Successor and Predecessor periods of 2021 and deposit for the purchase of wireless licenses in the three and nine months ended September 30, 2020