Products and Services Revenue - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Operating revenues	$ 1,801	$ 2,011	$ 5,518	$ 6,069
IP and Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	130	161	397	446
Transport and Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	649	703	1,957	2,100
Voice and Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	376	397	1,151	1,234
IT and Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	1	1	2	3
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	44	48	135	143
Affiliate services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 601	$ 701	$ 1,876	$ 2,143