Changes in Carrying Amount of Goodwill (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Wireless Licenses, Goodwill and Other Intangible Assets [Line Items]
Balance at January 1, 2013	$ 24,139
Acquisitions	203
Reclassifications, adjustments and other	(6)
Balance at June 30, 2013	24,336
Wireless
Wireless Licenses, Goodwill and Other Intangible Assets [Line Items]
Balance at January 1, 2013	18,172
Acquisitions	203
Balance at June 30, 2013	18,375
Wireline
Wireless Licenses, Goodwill and Other Intangible Assets [Line Items]
Balance at January 1, 2013	5,967
Reclassifications, adjustments and other	(6)
Balance at June 30, 2013	$ 5,961