Employee Benefit Plan, Investments (Plan Interest in Investment Fund) (Details) - USD ($)
$ in Thousands |
Dec. 31, 2025 |
Dec. 31, 2024 |
| EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Asset |
$ 2,691,149
|
$ 2,528,777
|
| Group Trust net asset |
2,689,497
|
2,527,465
|
| Investment at Fair Value |
2,645,412
|
2,478,101
|
| EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
11,301,767
|
11,321,338
|
| Investment at Fair Value |
7,170,886
|
6,862,851
|
| Mortgage-backed securities | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
816,124
|
843,105
|
| Corporate debt | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
874,643
|
939,989
|
| Government securities | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
505,762
|
319,763
|
| Common/collective trust funds | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
3,807,953
|
3,962,205
|
| Equities | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
989,007
|
589,466
|
| Registered investment companies | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
174,429
|
202,817
|
| Futures | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
2,534
|
| Investment at Fair Value |
23
|
|
| Other Investments | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
2,131,205
|
1,958,663
|
| Other Investments | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
430,606
|
(420,560)
|
| Assets at contract value |
4,561,487
|
4,879,047
|
| Non-US [Member] | Foreign cash | EBP-43-1301883-021 [Group Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Investment at Fair Value |
2,945
|
8,040
|
| AT&T Total Return Bond Fund | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
2,620,014
|
2,470,068
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
3,047,692
|
2,888,795
|
| AT&T Total Return Bond Fund | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
73,167
|
60,587
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
85,110
|
70,858
|
| AT&T Total Return Bond Fund | Mortgage-backed securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
793,952
|
822,920
|
| AT&T Total Return Bond Fund | Mortgage-backed securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
22,172
|
20,185
|
| AT&T Total Return Bond Fund | Corporate debt | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
850,881
|
916,579
|
| AT&T Total Return Bond Fund | Corporate debt | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
23,762
|
22,482
|
| AT&T Total Return Bond Fund | Government securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
492,022
|
312,107
|
| AT&T Total Return Bond Fund | Government securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
13,740
|
7,656
|
| AT&T Total Return Bond Fund | Common/collective trust funds | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
887,253
|
815,461
|
| AT&T Total Return Bond Fund | Common/collective trust funds | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
24,777
|
20,002
|
| AT&T Total Return Bond Fund | Equities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Total Return Bond Fund | Equities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Total Return Bond Fund | Registered investment companies | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
21,134
|
16,868
|
| AT&T Total Return Bond Fund | Registered investment companies | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
590
|
414
|
| AT&T Total Return Bond Fund | Futures | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
2,473
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
22
|
|
| AT&T Total Return Bond Fund | Futures | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
61
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
1
|
|
| AT&T Total Return Bond Fund | Other Investments | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
427,678
|
418,727
|
| Assets at contract value |
0
|
0
|
| AT&T Total Return Bond Fund | Other Investments | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
11,943
|
10,271
|
| Assets at contract value |
0
|
0
|
| AT&T Total Return Bond Fund | Non-US [Member] | Foreign cash | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
2,428
|
7,333
|
| AT&T Total Return Bond Fund | Non-US [Member] | Foreign cash | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
68
|
180
|
| AT&T U.S. Stock Fund | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
3,328,355
|
3,247,966
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
3,328,213
|
3,248,098
|
| AT&T U.S. Stock Fund | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
37,867
|
30,488
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
37,865
|
30,489
|
| AT&T U.S. Stock Fund | Mortgage-backed securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Mortgage-backed securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Corporate debt | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Corporate debt | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Government securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Government securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T U.S. Stock Fund | Common/collective trust funds | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
2,441,849
|
2,756,137
|
| AT&T U.S. Stock Fund | Common/collective trust funds | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
27,781
|
25,871
|
| AT&T U.S. Stock Fund | Equities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
851,739
|
466,275
|
| AT&T U.S. Stock Fund | Equities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
9,690
|
4,377
|
| AT&T U.S. Stock Fund | Registered investment companies | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
34,622
|
25,683
|
| AT&T U.S. Stock Fund | Registered investment companies | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
394
|
241
|
| AT&T U.S. Stock Fund | Futures | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T U.S. Stock Fund | Futures | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T U.S. Stock Fund | Other Investments | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(142)
|
132
|
| Assets at contract value |
0
|
0
|
| AT&T U.S. Stock Fund | Other Investments | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(2)
|
1
|
| Assets at contract value |
0
|
0
|
| AT&T U.S. Stock Fund | Non-US [Member] | Foreign cash | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
3
|
3
|
| AT&T U.S. Stock Fund | Non-US [Member] | Foreign cash | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T International Stock Fund | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
539,929
|
457,631
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
539,031
|
457,055
|
| AT&T International Stock Fund | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
17,066
|
12,472
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
17,038
|
12,456
|
| AT&T International Stock Fund | Mortgage-backed securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T International Stock Fund | Mortgage-backed securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T International Stock Fund | Corporate debt | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
903
|
| AT&T International Stock Fund | Corporate debt | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
25
|
| AT&T International Stock Fund | Government securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T International Stock Fund | Government securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T International Stock Fund | Common/collective trust funds | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
413,231
|
335,590
|
| AT&T International Stock Fund | Common/collective trust funds | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
13,062
|
9,144
|
| AT&T International Stock Fund | Equities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
123,671
|
115,662
|
| AT&T International Stock Fund | Equities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
3,907
|
3,152
|
| AT&T International Stock Fund | Registered investment companies | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
1,698
|
4,391
|
| AT&T International Stock Fund | Registered investment companies | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
54
|
120
|
| AT&T International Stock Fund | Futures | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T International Stock Fund | Futures | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T International Stock Fund | Other Investments | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(898)
|
(576)
|
| Assets at contract value |
0
|
0
|
| AT&T International Stock Fund | Other Investments | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(28)
|
(16)
|
| Assets at contract value |
0
|
0
|
| AT&T International Stock Fund | Non-US [Member] | Foreign cash | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
431
|
509
|
| AT&T International Stock Fund | Non-US [Member] | Foreign cash | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
15
|
15
|
| AT&T Stable Value Fund | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
4,299,262
|
4,626,235
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
106,383
|
142,307
|
| AT&T Stable Value Fund | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Group Trust net asset |
386,107
|
415,891
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
9,554
|
12,793
|
| AT&T Stable Value Fund | Mortgage-backed securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Mortgage-backed securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Corporate debt | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Corporate debt | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Government securities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Government securities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Common/collective trust funds | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Common/collective trust funds | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Equities | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Equities | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Registered investment companies | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
106,383
|
142,307
|
| AT&T Stable Value Fund | Registered investment companies | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
9,554
|
12,793
|
| AT&T Stable Value Fund | Futures | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T Stable Value Fund | Futures | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
|
0
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
|
| AT&T Stable Value Fund | Other Investments | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(7,290)
|
(7,321)
|
| Assets at contract value |
4,185,589
|
4,476,607
|
| AT&T Stable Value Fund | Other Investments | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| Liability (Asset) at Fair Value |
(655)
|
(658)
|
| Assets at contract value |
375,898
|
402,440
|
| AT&T Stable Value Fund | Non-US [Member] | Foreign cash | EBP-43-1301883-022 [Master Trust] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
0
|
0
|
| AT&T Stable Value Fund | Non-US [Member] | Foreign cash | EBP-58-1533433-004 [BSSP] |
|
|
| EBP, Investments [Line Items] |
|
|
| EBP, Investment, Plan Interest in Master Trust, Fair Value |
$ 0
|
$ 0
|