Products and Services Revenues - Revenue From Products and Services (Details) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended							10 Months Ended	12 Months Ended
	Oct. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Oct. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Revenue from External Customer [Line Items]
Total operating revenue		$ 1,407	$ 2,071	$ 2,010	$ 2,052	$ 2,087				$ 6,870	$ 8,220	$ 8,277	$ 8,173
USF contributions		$ 71									$ 415
Number of reportable segments | segment											1
Customer Concentration Risk | Sales Revenue
Revenue from External Customer [Line Items]
Concentration risk, percentage		19.00%									20.00%
Predecessor
Revenue from External Customer [Line Items]
Total operating revenue	$ 701						$ 2,059	$ 2,062	$ 2,048	6,870			8,173
USF contributions										$ 331			$ 414
Predecessor | Customer Concentration Risk | Sales Revenue
Revenue from External Customer [Line Items]
Concentration risk, percentage										18.00%			16.00%
IP and Data Services
Revenue from External Customer [Line Items]
Total operating revenue		$ 668								$ 3,284	$ 3,945		$ 3,862
Transport and Infrastructure
Revenue from External Customer [Line Items]
Total operating revenue		464								2,272	2,699		2,703
Voice and Collaboration
Revenue from External Customer [Line Items]
Total operating revenue		258								1,308	1,464		1,600
Other revenue
Revenue from External Customer [Line Items]
Total operating revenue		1								6	5		8
Affiliate revenue
Revenue from External Customer [Line Items]
Total operating revenue		$ 16								0	$ 107		0
Affiliate revenue | Predecessor
Revenue from External Customer [Line Items]
Total operating revenue										$ 0			$ 0