Operating Financial Information for Reportable Segments (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Operating Revenues	$ 31,984us-gaap_Revenues	$ 30,818us-gaap_Revenues
Operating income	7,960us-gaap_OperatingIncomeLoss	7,160us-gaap_OperatingIncomeLoss
Wireless
Segment Reporting Information [Line Items]
Operating Revenues	22,328	20,879
Operating income	7,810	7,318
Wireline
Segment Reporting Information [Line Items]
Operating Revenues	9,469	9,662
Operating income	405	141
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	31,797	30,541
Operating income	8,215	7,459
Operating Segments \| Wireless
Segment Reporting Information [Line Items]
Operating Revenues	22,302	20,851
Operating Segments \| Wireless \| Service Revenue Retail Service
Segment Reporting Information [Line Items]
Operating Revenues	17,131	17,233
Operating Segments \| Wireless \| Service Revenue Other Service
Segment Reporting Information [Line Items]
Operating Revenues	765	735
Operating Segments \| Wireless \| Service Revenue
Segment Reporting Information [Line Items]
Operating Revenues	17,896	17,968
Operating Segments \| Wireless \| Equipment
Segment Reporting Information [Line Items]
Operating Revenues	3,373	1,869
Operating Segments \| Wireless \| Other
Segment Reporting Information [Line Items]
Operating Revenues	1,033	1,014
Operating Segments \| Wireline
Segment Reporting Information [Line Items]
Operating Revenues	9,208	9,406
Operating Segments \| Wireline \| Other
Segment Reporting Information [Line Items]
Operating Revenues	87	140
Operating Segments \| Wireline \| Mass Markets Consumer Retail
Segment Reporting Information [Line Items]
Operating Revenues	3,992	3,840
Operating Segments \| Wireline \| Mass Markets Small Business
Segment Reporting Information [Line Items]
Operating Revenues	600	624
Operating Segments \| Wireline \| Mass Markets
Segment Reporting Information [Line Items]
Operating Revenues	4,592	4,464
Operating Segments \| Wireline \| Global Enterprise Strategic Services
Segment Reporting Information [Line Items]
Operating Revenues	2,048	2,062
Operating Segments \| Wireline \| Global Enterprise Core
Segment Reporting Information [Line Items]
Operating Revenues	1,215	1,404
Operating Segments \| Wireline \| Global Enterprise
Segment Reporting Information [Line Items]
Operating Revenues	3,263	3,466
Operating Segments \| Wireline \| Global Wholesale
Segment Reporting Information [Line Items]
Operating Revenues	1,266	1,336
Operating Segments \| Total Segments
Segment Reporting Information [Line Items]
Operating Revenues	31,510	30,257
Operating Segments \| Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Operating Revenues	474	561
Intersegment Revenues \| Wireless
Segment Reporting Information [Line Items]
Operating Revenues	26	28
Intersegment Revenues \| Wireline
Segment Reporting Information [Line Items]
Operating Revenues	261	256
Intersegment Revenues \| Total Segments
Segment Reporting Information [Line Items]
Operating Revenues	287	284
Intersegment Revenues \| Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Operating Revenues	(287)	(284)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Operating Revenues	187	277
Operating income	$ (255)	$ (299)

Operating Financial Information for Reportable Segments (Detail) (USD $)
In Millions, unless otherwise specified

3 Months Ended

Mar. 31, 2015

Mar. 31, 2014

Segment Reporting Information [Line Items]