Revenue Recognition - Revenue by Segment, Sales Channel and Product Category (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,887	$ 5,167	$ 14,840	$ 15,587
Adjustments for non-ASC 606 revenue	(472)	(481)	(1,417)	(1,443)
Total revenue from contracts with customers	4,415	4,686	13,423	14,144
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	4,887	5,167	14,840	15,587
Operating Segments | Business
Disaggregation of Revenue [Line Items]
Total revenue	3,508	3,698	10,625	11,152
Adjustments for non-ASC 606 revenue	(273)	(272)	(820)	(814)
Total revenue from contracts with customers	3,235	3,426	9,805	10,338
Operating Segments | Business | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	431	434	1,295	1,301
Adjustments for non-ASC 606 revenue	(133)	(132)	(400)	(394)
Total revenue from contracts with customers	298	302	895	907
Operating Segments | Business | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	1,545	1,595	4,675	4,825
Adjustments for non-ASC 606 revenue	(1)	(2)	(4)	(5)
Total revenue from contracts with customers	1,544	1,593	4,671	4,820
Operating Segments | Business | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	575	579	1,680	1,673
Adjustments for non-ASC 606 revenue	(76)	(74)	(228)	(218)
Total revenue from contracts with customers	499	505	1,452	1,455
Operating Segments | Business | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	957	1,090	2,975	3,353
Adjustments for non-ASC 606 revenue	(63)	(64)	(188)	(197)
Total revenue from contracts with customers	894	1,026	2,787	3,156
Operating Segments | Business | International and Global Accounts
Disaggregation of Revenue [Line Items]
Total revenue	1,019	1,013	3,036	3,085
Adjustments for non-ASC 606 revenue	(104)	(94)	(305)	(281)
Total revenue from contracts with customers	915	919	2,731	2,804
Operating Segments | Business | International and Global Accounts | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	178	188	536	581
Adjustments for non-ASC 606 revenue	(71)	(66)	(210)	(199)
Total revenue from contracts with customers	107	122	326	382
Operating Segments | Business | International and Global Accounts | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	429	431	1,283	1,300
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	429	431	1,283	1,300
Operating Segments | Business | International and Global Accounts | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	230	206	662	610
Adjustments for non-ASC 606 revenue	(33)	(28)	(95)	(82)
Total revenue from contracts with customers	197	178	567	528
Operating Segments | Business | International and Global Accounts | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	182	188	555	594
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	182	188	555	594
Operating Segments | Business | Large Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	932	990	2,800	2,929
Adjustments for non-ASC 606 revenue	(27)	(35)	(85)	(98)
Total revenue from contracts with customers	905	955	2,715	2,831
Operating Segments | Business | Large Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	176	167	513	481
Adjustments for non-ASC 606 revenue	(16)	(22)	(47)	(61)
Total revenue from contracts with customers	160	145	466	420
Operating Segments | Business | Large Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	387	393	1,170	1,194
Adjustments for non-ASC 606 revenue	0	(1)	0	(2)
Total revenue from contracts with customers	387	392	1,170	1,192
Operating Segments | Business | Large Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	137	162	388	436
Adjustments for non-ASC 606 revenue	(11)	(12)	(38)	(35)
Total revenue from contracts with customers	126	150	350	401
Operating Segments | Business | Large Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	232	268	729	818
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	232	268	729	818
Operating Segments | Business | Mid-Market Enterprise
Disaggregation of Revenue [Line Items]
Total revenue	666	737	2,064	2,253
Adjustments for non-ASC 606 revenue	(10)	(5)	(33)	(25)
Total revenue from contracts with customers	656	732	2,031	2,228
Operating Segments | Business | Mid-Market Enterprise | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	31	32	103	101
Adjustments for non-ASC 606 revenue	(7)	(3)	(23)	(14)
Total revenue from contracts with customers	24	29	80	87
Operating Segments | Business | Mid-Market Enterprise | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	432	460	1,323	1,389
Adjustments for non-ASC 606 revenue	(1)	(1)	(4)	(3)
Total revenue from contracts with customers	431	459	1,319	1,386
Operating Segments | Business | Mid-Market Enterprise | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	53	54	166	165
Adjustments for non-ASC 606 revenue	(2)	(1)	(6)	(8)
Total revenue from contracts with customers	51	53	160	157
Operating Segments | Business | Mid-Market Enterprise | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	150	191	472	598
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	150	191	472	598
Operating Segments | Business | Wholesale
Disaggregation of Revenue [Line Items]
Total revenue	891	958	2,725	2,885
Adjustments for non-ASC 606 revenue	(132)	(138)	(397)	(410)
Total revenue from contracts with customers	759	820	2,328	2,475
Operating Segments | Business | Wholesale | Compute and Application Services
Disaggregation of Revenue [Line Items]
Total revenue	46	47	143	138
Adjustments for non-ASC 606 revenue	(39)	(41)	(120)	(120)
Total revenue from contracts with customers	7	6	23	18
Operating Segments | Business | Wholesale | IP and Data Services
Disaggregation of Revenue [Line Items]
Total revenue	297	311	899	942
Adjustments for non-ASC 606 revenue	0	0	0	0
Total revenue from contracts with customers	297	311	899	942
Operating Segments | Business | Wholesale | Fiber Infrastructure Services
Disaggregation of Revenue [Line Items]
Total revenue	155	157	464	462
Adjustments for non-ASC 606 revenue	(30)	(33)	(89)	(93)
Total revenue from contracts with customers	125	124	375	369
Operating Segments | Business | Wholesale | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	393	443	1,219	1,343
Adjustments for non-ASC 606 revenue	(63)	(64)	(188)	(197)
Total revenue from contracts with customers	330	379	1,031	1,146
Operating Segments | Mass Markets
Disaggregation of Revenue [Line Items]
Total revenue	1,379	1,469	4,215	4,435
Adjustments for non-ASC 606 revenue	(199)	(209)	(597)	(629)
Total revenue from contracts with customers	1,180	1,260	3,618	3,806
Operating Segments | Mass Markets | Voice and Other
Disaggregation of Revenue [Line Items]
Total revenue	502	578	1,561	1,772
Adjustments for non-ASC 606 revenue	(20)	(27)	(60)	(85)
Total revenue from contracts with customers	482	551	1,501	1,687
Operating Segments | Mass Markets | Consumer Broadband
Disaggregation of Revenue [Line Items]
Total revenue	715	730	2,169	2,178
Adjustments for non-ASC 606 revenue	(52)	(56)	(157)	(164)
Total revenue from contracts with customers	663	674	2,012	2,014
Operating Segments | Mass Markets | SBG Broadband
Disaggregation of Revenue [Line Items]
Total revenue	39	38	117	116
Adjustments for non-ASC 606 revenue	(4)	(3)	(12)	(11)
Total revenue from contracts with customers	35	35	105	105
Operating Segments | Mass Markets | CAF II
Disaggregation of Revenue [Line Items]
Total revenue	123	123	368	369
Adjustments for non-ASC 606 revenue	(123)	(123)	(368)	(369)
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0