Pension And Postretirement Benefits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension And Postretirement Benefits
Combined net pension and postretirement cost decrease	$ 46		$ 86
Net supplemental retirement pension benefits costs	32	36	63	71
Net supplemental retirement pension benefits costs - interest cost	$ 29	$ 32	$ 58	$ 63

Change in combined net pension and other postretirement cost relative to the a comparable prior year period

No definition available.

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Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration