EFFECTS OF REGULATION - Regulatory Assets - PSO (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Regulatory Asset [Line Items]
Total Current Regulatory Assets	$ 426	$ 446
Total Noncurrent Regulatory Assets	4,804	5,129
Pending final regulatory approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	1,307	1,311
Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	3,497	3,818
Earns/earning a return | Under-recovered Fuel Costs
Regulatory Asset [Line Items]
Total Current Regulatory Assets	$ 140	246
Remaining Recovery Period	1 year
Earns/earning a return | Pending final regulatory approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 435	395
Earns/earning a return | Pending final regulatory approval | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	43	51
Earns/earning a return | Pending final regulatory approval | Other Regulatory Assets Pending Final Regulatory Approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	23	21
Earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	1,341	1,711
Earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 100	107
Remaining Recovery Period	6 years
Earns/earning a return | Approved for recovery | Plant Retirement Costs - Unrecovered Plant
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 470	661
Remaining Recovery Period	21 years
Earns/earning a return | Approved for recovery | Environmental Control Projects
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 27	29
Remaining Recovery Period	15 years
Earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 199	204
Does not earns/earning a return | Under-recovered Fuel Costs
Regulatory Asset [Line Items]
Total Current Regulatory Assets	$ 202	116
Remaining Recovery Period	1 year
Does not earns/earning a return | Pending final regulatory approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 872	916
Does not earns/earning a return | Pending final regulatory approval | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	191	301
Does not earns/earning a return | Pending final regulatory approval | Other Regulatory Assets Pending Final Regulatory Approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	163	87
Does not earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	2,156	2,107
Does not earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 158	67
Remaining Recovery Period	6 years
Does not earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 222	229
Does not earns/earning a return | Approved for recovery | Pension and OPEB Funded Status
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 796	974
Remaining Recovery Period	12 years
Does not earns/earning a return | Approved for recovery | Unrealized Loss on Forward Commitments
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 69	53
Remaining Recovery Period	7 years
PUBLIC SERVICE COMPANY OF OKLAHOMA
Regulatory Asset [Line Items]
Total Current Regulatory Assets	$ 37	65
Total Noncurrent Regulatory Assets	637	528
PUBLIC SERVICE COMPANY OF OKLAHOMA | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	553	498
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Under-recovered Fuel Costs
Regulatory Asset [Line Items]
Total Current Regulatory Assets	$ 37	65
Remaining Recovery Period	1 year
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 434	426
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 90	107
Remaining Recovery Period	6 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery | Plant Retirement Costs - Unrecovered Plant
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 302	274
Remaining Recovery Period	21 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery | Environmental Control Projects
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 20	21
Remaining Recovery Period	15 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery | Meter Replacement Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 6	10
Remaining Recovery Period	2 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 16	14
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Pending final regulatory approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	84	30
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Pending final regulatory approval | Storm-Related Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	25	5
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Pending final regulatory approval | NOCL - Costs
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	23	16
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Pending final regulatory approval | Generation PBA and Delayed Retirement Deferral
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	13	0
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Pending final regulatory approval | Other Regulatory Assets Pending Final Regulatory Approval
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	23	9
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Approved for recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	119	72
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Approved for recovery | Other Regulatory Assets Approved for Recovery
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	12	10
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Approved for recovery | Pension and OPEB Funded Status
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 41	58
Remaining Recovery Period	12 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Approved for recovery | Renewable Resources Rider
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 38	0
Remaining Recovery Period	2 years
PUBLIC SERVICE COMPANY OF OKLAHOMA | Does not earns/earning a return | Approved for recovery | Unrealized Loss on Forward Commitments
Regulatory Asset [Line Items]
Total Noncurrent Regulatory Assets	$ 28	$ 4
Remaining Recovery Period	2 years