Products and Services Revenue - Operating Revenues for Products and Services (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) category	Sep. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Number of categories of products and services | category			5
Operating revenues	$ 2,064	$ 2,010	$ 6,124	$ 6,149
IP and Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	972	970	2,917	2,961
Transport and Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	668	664	1,981	2,013
Voice and Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	379	349	1,085	1,094
Other
Disaggregation of Revenue [Line Items]
Operating revenues	4	1	7	3
Affiliate Services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 41	$ 26	$ 134	$ 78