Summary of Reconciliation of Segment Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Assets	$ 223,346	$ 225,222
Wireless
Segment Reporting Information [Line Items]
Assets	142,997	142,485
Wireline
Segment Reporting Information [Line Items]
Assets	85,549	84,815
Total Segments
Segment Reporting Information [Line Items]
Assets	228,546	227,300
Reconciling Items
Segment Reporting Information [Line Items]
Assets	$ (5,200)	$ (2,078)