Segment Information - Operating Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating revenues by products and services
Revenues	$ 5,902	$ 4,090	$ 11,847	$ 8,299
Surcharge amount on customers' bills	229	133	476	263
Business
Operating revenues by products and services
Revenues	4,365	2,470	8,748	5,060
Consumer
Operating revenues by products and services
Revenues	1,352	1,437	2,731	2,884
Operating segments
Operating revenues by products and services
Revenues	5,717	3,907	11,479	7,944
Operating segments | Business
Operating revenues by products and services
Revenues	4,365	2,470	8,748	5,060
Operating segments | Business | IP & Data Services
Operating revenues by products and services
Revenues	1,748	744	3,485	1,501
Operating segments | Business | Transport & Infrastructure
Operating revenues by products and services
Revenues	1,342	797	2,691	1,691
Operating segments | Business | Voice & Collaboration
Operating revenues by products and services
Revenues	1,111	767	2,247	1,554
Operating segments | Business | IT & Managed Services
Operating revenues by products and services
Revenues	164	162	325	314
Operating segments | Consumer
Operating revenues by products and services
Revenues	1,352	1,437	2,731	2,884
Operating segments | Consumer | IP & Data Services
Operating revenues by products and services
Revenues	85	107	179	210
Operating segments | Consumer | Transport & Infrastructure
Operating revenues by products and services
Revenues	722	683	1,451	1,366
Operating segments | Consumer | Voice & Collaboration
Operating revenues by products and services
Revenues	545	647	1,101	1,308
Corporate, Non-Segment
Operating revenues by products and services
Revenues	185	183	368	355
Corporate, Non-Segment | Regulatory Revenue
Operating revenues by products and services
Revenues	$ 185	$ 183	$ 368	$ 355