Products and Services Revenues - Operating Revenues by Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Products and Services Revenues
Operating revenues	$ 2,130	$ 2,162
IP & Data Services
Products and Services Revenues
Operating revenues	146	151
Transport & Infrastructure
Products and Services Revenues
Operating revenues	759	769
Voice & Collaboration
Products and Services Revenues
Operating revenues	460	511
IT & Managed Services
Products and Services Revenues
Operating revenues	2	1
Regulatory Revenue
Products and Services Revenues
Operating revenues	52	54
Affiliate services
Products and Services Revenues
Operating revenues	$ 711	$ 676