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	$ 2,014	$ 2,052	$ 4,060	$ 4,139
IP & Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	965	988	1,945	1,991
Transport & Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	655	673	1,313	1,349
Voice & Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	355	363	706	745
Other
Disaggregation of Revenue [Line Items]
Operating revenues	1	1	3	2
Affiliate Revenues
Disaggregation of Revenue [Line Items]
Operating revenues	$ 38	$ 27	$ 93	$ 52