Products and Services Revenues (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) category segment		Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Products and Services Revenues
Number of categories of products and services (categories) | category									6
Operating revenue	$ 2,113	$ 2,149	$ 2,101	$ 2,130	$ 2,114	$ 2,141	$ 2,133	$ 2,162	$ 8,493		$ 8,550	$ 8,910
Taxes and surcharges included in operating revenues and expenses									$ 124		134	149
Number of reportable segments | segment									1
IP and Data Services
Products and Services Revenues
Operating revenue									$ 616	[1]	634	667
Transport and Infrastructure
Products and Services Revenues
Operating revenue									2,926	[2]	3,006	3,109
Voice and Collaboration
Products and Services Revenues
Operating revenue									1,800	[3]	1,980	2,252
IT and Managed Services
Products and Services Revenues
Operating revenue									6	[4]	0	2
Regulatory Services
Products and Services Revenues
Operating revenue									210	[5]	211	217
Affiliate Services
Products and Services Revenues
Operating revenue									$ 2,935	[6]	$ 2,719	$ 2,663

[1] Includes primarily VPN data networks, Ethernet, IP and other ancillary services

[2] Includes primarily broadband, private line (including business data services) and other ancillary services.

[3] Includes local voice, including wholesale voice, and other ancillary services.

[4] Includes IT services and managed services revenue.

[5] Includes CAF II and federal and state USF support revenue.

[6] Includes telecommunications and data services we bill to our affiliates.