v3.25.4
Other Comprehensive Income (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Other comprehensive income (loss) before reclassifications $ (281) $ (184) $ 1,439
Amounts reclassified from accumulated OCI (1,374) (1,321) (1,905)
Other comprehensive income (loss) attributable to AT&T (1,655) (1,505) (466)
Accumulated Other Comprehensive Income      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Accumulated other comprehensive income, beginning balance 795 2,300 2,766
Other comprehensive income (loss) attributable to AT&T (1,655) (1,505) (466)
Accumulated other comprehensive income, ending balance (860) 795 2,300
Foreign Currency Translation Adjustment      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Accumulated other comprehensive income, beginning balance (1,755) (1,337) (1,800)
Other comprehensive income (loss) before reclassifications 354 (545) 463
Amounts reclassified from accumulated OCI 0 127 0
Other comprehensive income (loss) attributable to AT&T 354 (418) 463
Accumulated other comprehensive income, ending balance (1,401) (1,755) (1,337)
Net Unrealized Gains (Losses) on Securities      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Accumulated other comprehensive income, beginning balance (46) (57) (90)
Other comprehensive income (loss) before reclassifications 15 (19) 22
Amounts reclassified from accumulated OCI 3 30 11
Other comprehensive income (loss) attributable to AT&T 18 11 33
Accumulated other comprehensive income, ending balance (28) (46) (57)
Net Unrealized Gains (Losses) on Derivative Instruments      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Accumulated other comprehensive income, beginning balance (604) (1,029) (1,998)
Other comprehensive income (loss) before reclassifications (650) 380 922
Amounts reclassified from accumulated OCI 45 45 47
Other comprehensive income (loss) attributable to AT&T (605) 425 969
Accumulated other comprehensive income, ending balance (1,209) (604) (1,029)
Defined Benefit Postretirement Plans      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Accumulated other comprehensive income, beginning balance 3,200 4,723 6,654
Other comprehensive income (loss) before reclassifications 0 0 32
Amounts reclassified from accumulated OCI (1,422) (1,523) (1,963)
Other comprehensive income (loss) attributable to AT&T (1,422) (1,523) (1,931)
Accumulated other comprehensive income, ending balance $ 1,778 $ 3,200 $ 4,723