Products and Services Revenues - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Operating revenues	$ 2,149	$ 2,141	$ 6,380	$ 6,436
IP & Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	155	161	460	475
Transport & Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	739	751	2,216	2,268
Voice & Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	448	492	1,370	1,504
IT & Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	2	0	6	0
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	53	52	157	159
Affiliate services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 752	$ 685	$ 2,171	$ 2,030