Severance and Leased Real Estate (Details) - USD ($) $ in Millions	2 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2017	Oct. 31, 2017	Dec. 31, 2018
Employee Severance
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 1		$ 5
Accrued to expense	6		33
Payments, net	(2)		(19)
Restructuring reserve, ending balance	5	$ 1	19
Property Subject to Operating Lease
Restructuring Reserve [Roll Forward]
Payments, net	(1)		(8)
Qwest Communications International Inc | Property Subject to Operating Lease
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, current			8
Restructuring reserve, noncurrent			$ 39
Weighted average lease term			8 years 2 months
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	5		$ 4
Accrued to expense	0		51
Restructuring reserve, ending balance	4	5	$ 47
Predecessor | Employee Severance
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	1	2
Accrued to expense		0
Payments, net		(1)
Restructuring reserve, ending balance		1
Predecessor | Property Subject to Operating Lease
Restructuring Reserve [Roll Forward]
Payments, net		(2)
Predecessor | Qwest Communications International Inc | Property Subject to Operating Lease
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 5	5
Accrued to expense		2
Restructuring reserve, ending balance		$ 5
Minimum | Qwest Communications International Inc | Property Subject to Operating Lease
Restructuring Cost and Reserve [Line Items]
Lease term			1 year
Maximum | Qwest Communications International Inc | Property Subject to Operating Lease
Restructuring Cost and Reserve [Line Items]
Lease term			12 years