Business, Significant Accounting Policies, Significant Events, and Recent Developments - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2024 USD ($)	Sep. 30, 2025 USD ($) MW	Mar. 31, 2025 USD ($) MW	Sep. 30, 2025 USD ($) segment MW	Oct. 31, 2025 USD ($)	Jul. 31, 2025 MW	Jun. 30, 2025 USD ($)	Jan. 16, 2025 facility MW	Nov. 27, 2024 MW
Line of Credit Facility [Line Items]
Number of reportable segments | segment				5
Property, plant and equipment — net	$ 18,173	$ 17,725		$ 17,725
Other current liabilities	645	687		687
Other noncurrent liabilities	1,270	1,454		1,454
Insurance settlements receivable	0	301		301			$ 324
Insurance recoveries		0		80
Interest costs incurred		4		24
Debt facility borrowings		9,134		9,134
Subsequent Event | Incremental Share Repurchase Program Approved By The Board Of Directors In August 2022
Line of Credit Facility [Line Items]
Stock repurchase program, authorized amount					$ 1,000
Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt facility borrowings					100
Senior Secured Notes Due | Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt instrument, face amount					2,000
4.300% Senior Secured Notes Due 2028 | Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt instrument, face amount					$ 750
Debt instrument, interest rate, stated percentage					4.30%
4.600% Senior Secured Notes Due 2030 | Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt instrument, face amount					$ 500
Debt instrument, interest rate, stated percentage					4.60%
5.250% Senior Secured Notes Due 2035 | Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt instrument, face amount					$ 750
Debt instrument, interest rate, stated percentage					5.25%
5.500% Senior Secured Notes Due 2026 | Vistra Operations Senior Secured Notes | Subsequent Event
Line of Credit Facility [Line Items]
Debt instrument, face amount					$ 1,000
Debt instrument, interest rate, stated percentage					5.50%
ASAOC
Line of Credit Facility [Line Items]
Total costs				110
Interest costs incurred		0		102
Moss Landing Power Plant (Battery Storage Project)
Line of Credit Facility [Line Items]
Other current liabilities			$ 8
Insurance settlements receivable	0	297		297			304
Insurance recoveries		0		0
Interest costs incurred		0		0
Moss Landing Power Plant (Battery Storage Project) | Moss Landing Battery Energy Storage System Phase I
Line of Credit Facility [Line Items]
Battery energy storage system capacity | MW			300			300		300
Depreciation expense			$ 400
Insurance settlements, limit amount		$ 500		$ 500
Insurance settlements receivable			$ 425
Moss Landing Power Plant (Battery Storage Project) | Moss Landing Battery Energy Storage System Phases II and III
Line of Credit Facility [Line Items]
Number of battery facilities | facility								2
Moss Landing Power Plant (Battery Storage Project) | Moss Landing Battery Energy Storage System Phase III
Line of Credit Facility [Line Items]
Battery energy storage system capacity | MW								350
Moss Landing Power Plant (Battery Storage Project) | Moss Landing Battery Energy Storage System Phase II
Line of Credit Facility [Line Items]
Battery energy storage system capacity | MW		100		100				100
Property, plant and equipment — net		$ 165		$ 165
Moss Landing Power Plant (Battery Storage Project) | ASAOC
Line of Credit Facility [Line Items]
Total costs				110
Estimated liability costs incurred		29		29
Environmental remediation obligation		81		81
Other current liabilities		68		68
Other noncurrent liabilities		13		13
Interest costs incurred		0		102
Martin Lake Incident
Line of Credit Facility [Line Items]
Insurance settlements receivable	0	4		4			$ 20
Insurance recoveries		0		80
Interest costs incurred		4		24
Martin Lake Incident | ASAOC
Line of Credit Facility [Line Items]
Interest costs incurred		$ 0		0
Martin Lake Incident | ERCOT
Line of Credit Facility [Line Items]
Battery energy storage system capacity | MW									815
Depreciation expense	$ 1
Total cash capital expenditures				355
Capital expenditures incurred				155
Insurance recoveries				104
Interest costs incurred				24
Other income, net				$ 80