Revenue Recognition - Revenue by Segment, Sales Channel and Product Category (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,924	$ 5,192	$ 9,953	$ 10,420
Adjustments for non-ASC 606 revenue	(471)	(481)	(945)	(962)
Total revenue from contracts with customers	4,453	4,711	9,008	9,458
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	4,924	5,192	9,953	10,420
Operating Segments | Business
Disaggregation of Revenue [Line Items]
Total revenue	3,522	3,717	7,117	7,454
Adjustments for non-ASC 606 revenue	(273)	(269)	(547)	(542)
Total revenue from contracts with customers	3,249	3,448	6,570	6,912
Operating Segments | Business | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	436	432	864	867
Adjustments for non-ASC 606 revenue	(135)	(128)	(267)	(262)
Total revenue from contracts with customers	301	304	597	605
Operating Segments | Business | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	1,550	1,608	3,130	3,230
Adjustments for non-ASC 606 revenue	(2)	(2)	(3)	(3)
Total revenue from contracts with customers	1,548	1,606	3,127	3,227
Operating Segments | Business | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	551	547	1,105	1,094
Adjustments for non-ASC 606 revenue	(74)	(74)	(152)	(144)
Total revenue from contracts with customers	477	473	953	950
Operating Segments | Business | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	985	1,130	2,018	2,263
Adjustments for non-ASC 606 revenue	(62)	(65)	(125)	(133)
Total revenue from contracts with customers	923	1,065	1,893	2,130
Operating Segments | Business | International and Global Accounts
Disaggregation of Revenue [Line Items]
Total revenue	1,004	1,031	2,017	2,072
Adjustments for non-ASC 606 revenue	(102)	(92)	(201)	(187)
Total revenue from contracts with customers	902	939	1,816	1,885
Operating Segments | Business | International and Global Accounts | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	179	192	358	393
Adjustments for non-ASC 606 revenue	(70)	(64)	(139)	(133)
Total revenue from contracts with customers	109	128	219	260
Operating Segments | Business | International and Global Accounts | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	427	432	854	869
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	427	432	854	869
Operating Segments | Business | International and Global Accounts | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	216	202	432	404
Adjustments for non-ASC 606 revenue	(32)	(28)	(62)	(54)
Total revenue from contracts with customers	184	174	370	350
Operating Segments | Business | International and Global Accounts | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	182	205	373	406
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	182	205	373	406
Operating Segments | Business | Large Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	931	973	1,868	1,939
Adjustments for non-ASC 606 revenue	(28)	(36)	(58)	(63)
Total revenue from contracts with customers	903	937	1,810	1,876
Operating Segments | Business | Large Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	172	160	337	314
Adjustments for non-ASC 606 revenue	(16)	(22)	(31)	(39)
Total revenue from contracts with customers	156	138	306	275
Operating Segments | Business | Large Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	388	400	783	801
Adjustments for non-ASC 606 revenue	0	(1)	0	(1)
Total revenue from contracts with customers	388	399	783	800
Operating Segments | Business | Large Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	127	136	251	274
Adjustments for non-ASC 606 revenue	(12)	(13)	(27)	(23)
Total revenue from contracts with customers	115	123	224	251
Operating Segments | Business | Large Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	244	277	497	550
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	244	277	497	550
Operating Segments | Business | Mid-Market Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	682	755	1,398	1,516
Adjustments for non-ASC 606 revenue	(12)	(7)	(23)	(20)
Total revenue from contracts with customers	670	748	1,375	1,496
Operating Segments | Business | Mid-Market Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	36	35	72	69
Adjustments for non-ASC 606 revenue	(8)	(3)	(16)	(11)
Total revenue from contracts with customers	28	32	56	58
Operating Segments | Business | Mid-Market Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	438	463	891	929
Adjustments for non-ASC 606 revenue	(2)	(1)	(3)	(2)
Total revenue from contracts with customers	436	462	888	927
Operating Segments | Business | Mid-Market Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	53	57	113	111
Adjustments for non-ASC 606 revenue	(2)	(3)	(4)	(7)
Total revenue from contracts with customers	51	54	109	104
Operating Segments | Business | Mid-Market Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	155	200	322	407
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	155	200	322	407
Operating Segments | Business | Wholesale
Disaggregation of Revenue [Line Items]
Total revenue	905	958	1,834	1,927
Adjustments for non-ASC 606 revenue	(131)	(134)	(265)	(272)
Total revenue from contracts with customers	774	824	1,569	1,655
Operating Segments | Business | Wholesale | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	49	45	97	91
Adjustments for non-ASC 606 revenue	(41)	(39)	(81)	(79)
Total revenue from contracts with customers	8	6	16	12
Operating Segments | Business | Wholesale | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	297	313	602	631
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	297	313	602	631
Operating Segments | Business | Wholesale | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	155	152	309	305
Adjustments for non-ASC 606 revenue	(28)	(30)	(59)	(60)
Total revenue from contracts with customers	127	122	250	245
Operating Segments | Business | Wholesale | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	404	448	826	900
Adjustments for non-ASC 606 revenue	(62)	(65)	(125)	(133)
Total revenue from contracts with customers	342	383	701	767
Operating Segments | Mass Markets
Disaggregation of Revenue [Line Items]
Total revenue	1,402	1,475	2,836	2,966
Adjustments for non-ASC 606 revenue	(198)	(212)	(398)	(420)
Total revenue from contracts with customers	1,204	1,263	2,438	2,546
Operating Segments | Mass Markets | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	518	587	1,059	1,194
Adjustments for non-ASC 606 revenue	(19)	(29)	(40)	(58)
Total revenue from contracts with customers	499	558	1,019	1,136
Operating Segments | Mass Markets | Consumer Broadband
Disaggregation of Revenue [Line Items]
Total revenue	723	726	1,454	1,448
Adjustments for non-ASC 606 revenue	(53)	(55)	(105)	(108)
Total revenue from contracts with customers	670	671	1,349	1,340
Operating Segments | Mass Markets | SBG Broadband
Disaggregation of Revenue [Line Items]
Total revenue	39	39	78	78
Adjustments for non-ASC 606 revenue	(4)	(5)	(8)	(8)
Total revenue from contracts with customers	35	34	70	70
Operating Segments | Mass Markets | CAF II
Disaggregation of Revenue [Line Items]
Total revenue	122	123	245	246
Adjustments for non-ASC 606 revenue	(122)	(123)	(245)	(246)
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0