Products and Services Revenue - Operating Revenues for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 2,039	$ 2,149	$ 6,145	$ 6,380
IP and Data Services
Disaggregation of Revenue [Line Items]
Operating revenues	169	155	467	459
Transport and Infrastructure
Disaggregation of Revenue [Line Items]
Operating revenues	716	739	2,140	2,215
Voice and Collaboration
Disaggregation of Revenue [Line Items]
Operating revenues	405	449	1,250	1,369
IT and Managed Services
Disaggregation of Revenue [Line Items]
Operating revenues	0	1	2	5
Regulatory Revenue
Disaggregation of Revenue [Line Items]
Operating revenues	48	53	143	161
Affiliate Services
Disaggregation of Revenue [Line Items]
Operating revenues	$ 701	$ 752	$ 2,143	$ 2,171