Revenue Recognition - Revenue by Segment, Sales Channel and Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 5,029	$ 5,228
Adjustments for non-ASC 606 revenue	(474)	(481)
Total revenue from contracts with customers	4,555	4,747
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	5,029	5,228
Operating Segments | Business
Disaggregation of Revenue [Line Items]
Total revenue	3,595	3,737
Adjustments for non-ASC 606 revenue	(274)	(273)
Total revenue from contracts with customers	3,321	3,464
Operating Segments | Business | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	428	435
Adjustments for non-ASC 606 revenue	(132)	(134)
Total revenue from contracts with customers	296	301
Operating Segments | Business | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	1,580	1,622
Adjustments for non-ASC 606 revenue	(1)	(1)
Total revenue from contracts with customers	1,579	1,621
Operating Segments | Business | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	554	547
Adjustments for non-ASC 606 revenue	(78)	(70)
Total revenue from contracts with customers	476	477
Operating Segments | Business | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	1,033	1,133
Adjustments for non-ASC 606 revenue	(63)	(68)
Total revenue from contracts with customers	970	1,065
Operating Segments | Business | International and Global Accounts
Disaggregation of Revenue [Line Items]
Total revenue	1,013	1,041
Adjustments for non-ASC 606 revenue	(99)	(95)
Total revenue from contracts with customers	914	946
Operating Segments | Business | International and Global Accounts | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	179	201
Adjustments for non-ASC 606 revenue	(69)	(69)
Total revenue from contracts with customers	110	132
Operating Segments | Business | International and Global Accounts | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	427	437
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	427	437
Operating Segments | Business | International and Global Accounts | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	216	202
Adjustments for non-ASC 606 revenue	(30)	(26)
Total revenue from contracts with customers	186	176
Operating Segments | Business | International and Global Accounts | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	191	201
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	191	201
Operating Segments | Business | Large Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	937	966
Adjustments for non-ASC 606 revenue	(30)	(27)
Total revenue from contracts with customers	907	939
Operating Segments | Business | Large Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	165	154
Adjustments for non-ASC 606 revenue	(15)	(17)
Total revenue from contracts with customers	150	137
Operating Segments | Business | Large Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	395	401
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	395	401
Operating Segments | Business | Large Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	124	138
Adjustments for non-ASC 606 revenue	(15)	(10)
Total revenue from contracts with customers	109	128
Operating Segments | Business | Large Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	253	273
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	253	273
Operating Segments | Business | Mid-Market Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	716	761
Adjustments for non-ASC 606 revenue	(11)	(13)
Total revenue from contracts with customers	705	748
Operating Segments | Business | Mid-Market Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	36	34
Adjustments for non-ASC 606 revenue	(8)	(8)
Total revenue from contracts with customers	28	26
Operating Segments | Business | Mid-Market Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	453	466
Adjustments for non-ASC 606 revenue	(1)	(1)
Total revenue from contracts with customers	452	465
Operating Segments | Business | Mid-Market Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	60	54
Adjustments for non-ASC 606 revenue	(2)	(4)
Total revenue from contracts with customers	58	50
Operating Segments | Business | Mid-Market Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	167	207
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	167	207
Operating Segments | Business | Wholesale
Disaggregation of Revenue [Line Items]
Total revenue	929	969
Adjustments for non-ASC 606 revenue	(134)	(138)
Total revenue from contracts with customers	795	831
Operating Segments | Business | Wholesale | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	48	46
Adjustments for non-ASC 606 revenue	(40)	(40)
Total revenue from contracts with customers	8	6
Operating Segments | Business | Wholesale | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	305	318
Adjustments for non-ASC 606 revenue	0	0
Total revenue from contracts with customers	305	318
Operating Segments | Business | Wholesale | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	154	153
Adjustments for non-ASC 606 revenue	(31)	(30)
Total revenue from contracts with customers	123	123
Operating Segments | Business | Wholesale | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	422	452
Adjustments for non-ASC 606 revenue	(63)	(68)
Total revenue from contracts with customers	359	384
Operating Segments | Mass Markets
Disaggregation of Revenue [Line Items]
Total revenue	1,434	1,491
Adjustments for non-ASC 606 revenue	(200)	(208)
Total revenue from contracts with customers	1,234	1,283
Operating Segments | Mass Markets | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	541	607
Adjustments for non-ASC 606 revenue	(21)	(29)
Total revenue from contracts with customers	520	578
Operating Segments | Mass Markets | Consumer Broadband
Disaggregation of Revenue [Line Items]
Total revenue	731	722
Adjustments for non-ASC 606 revenue	(52)	(53)
Total revenue from contracts with customers	679	669
Operating Segments | Mass Markets | SBG Broadband
Disaggregation of Revenue [Line Items]
Total revenue	39	39
Adjustments for non-ASC 606 revenue	(4)	(3)
Total revenue from contracts with customers	35	36
Operating Segments | Mass Markets | CAF II
Disaggregation of Revenue [Line Items]
Total revenue	123	123
Adjustments for non-ASC 606 revenue	(123)	(123)
Total revenue from contracts with customers	$ 0	$ 0