Products and Services Revenues - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Operating revenues	$ 2,101	$ 2,133	$ 4,231	$ 4,295
IP & Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	154	155	305	314
Transport & Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	732	757	1,477	1,517
Voice & Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	453	499	922	1,012
IT & Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	2	0	4	0
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	52	53	104	107
Affiliate services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 708	$ 669	$ 1,419	$ 1,345