Summary of Reconciliation of Segment Assets (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Assets	$ 226,186	$ 225,222
Wireless
Segment Reporting Information [Line Items]
Assets	145,242	142,485
Wireline
Segment Reporting Information [Line Items]
Assets	85,746	84,815
Total Segments
Segment Reporting Information [Line Items]
Assets	230,988	227,300
Reconciling Items
Segment Reporting Information [Line Items]
Assets	$ (4,802)	$ (2,078)