Products and Services Revenue - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 2,051	$ 2,101	$ 4,106	$ 4,231
IP and Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	151	154	298	305
Transport and Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	709	732	1,424	1,476
Voice and Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	423	453	845	920
IT and Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	1	2	2	3
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	47	52	95	108
Affiliate Services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 720	$ 708	$ 1,442	$ 1,419