Products and Services Revenue - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Operating revenues	$ 1,799	$ 2,028	$ 3,717	$ 4,058
IP and Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	131	145	267	285
Transport and Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	651	696	1,308	1,397
Voice and Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	380	419	775	837
IT and Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	0	1	1	2
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	45	47	91	95
Affiliate Services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 592	$ 720	$ 1,275	$ 1,442