Debt, Credit Facilities and Financings - Schedule of Long-Term Debt Instruments (Details) - USD ($) $ in Millions	Oct. 31, 2025	Sep. 30, 2025	May 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 15,988		$ 16,298
Total other long-term debt		55		55
Unamortized debt premiums, discounts and issuance costs		(142)		(171)
Less amounts due currently		(231)		(880)
Total long-term debt less amounts due currently		$ 15,757		15,418
Bridge Loans
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		1.625%
Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 4,400		5,144
Energy Harbor Revenue Bonds
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		431		431
Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		7,300		7,300
Vistra Operations Credit Facilities, Term Loan B-3 Facility due December 20, 2030 | Line of Credit
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		2,456		2,475
BCOP Credit Facility | Bridge Loans
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		367		367
BCOP Credit Facility | Construction / Term Loans
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		424		0
Vistra Zero Credit Facility, Term Loan B Facility due April 30, 2031 | Line of Credit
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		697		697
5.125% Senior Secured Notes, due May 13, 2025 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 0		744
Debt instrument, interest rate, stated percentage		5.125%	5.125%
Debt instrument, face amount			$ 744
5.050% Senior Secured Notes, due December 30, 2026 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 500		500
Debt instrument, interest rate, stated percentage		5.05%
3.700% Senior Secured Notes, due January 30, 2027 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 800		800
Debt instrument, interest rate, stated percentage		3.70%
4.300% Senior Secured Notes, due July 15, 2029 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 800		800
Debt instrument, interest rate, stated percentage		4.30%
6.950% Senior Secured Notes, due October 15, 2033 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,050		1,050
Debt instrument, interest rate, stated percentage		6.95%
6.000% Senior Secured Notes, due April 15, 2034 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 500		500
Debt instrument, interest rate, stated percentage		6.00%
5.700% Senior Secured Notes, due December 30, 2034 | Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 750		750
Debt instrument, interest rate, stated percentage		5.70%
3.375% Revenue Bond, due August 1, 2029 | Energy Harbor Revenue Bonds
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 100		100
Debt instrument, interest rate, stated percentage		3.375%
4.750% Revenue Bonds, due June 1, 2033 and July 1, 2033 | Energy Harbor Revenue Bonds
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 285		285
Debt instrument, interest rate, stated percentage		4.75%
3.750% Revenue Bond, due October 1, 2047 | Energy Harbor Revenue Bonds
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 46		46
Debt instrument, interest rate, stated percentage		3.75%
5.500% Senior Unsecured Notes, due September 1, 2026 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,000		1,000
Debt instrument, interest rate, stated percentage		5.50%
5.625% Senior Unsecured Notes, due February 15, 2027 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,300		1,300
Debt instrument, interest rate, stated percentage		5.625%
5.000% Senior Unsecured Notes, due July 31, 2027 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,300		1,300
Debt instrument, interest rate, stated percentage		5.00%
4.375% Senior Unsecured Notes, due May 1, 2029 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,250		1,250
Debt instrument, interest rate, stated percentage		4.375%
7.750% Senior Unsecured Notes, due October 15, 2031 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,450		1,450
Debt instrument, interest rate, stated percentage		7.75%
6.875% Senior Unsecured Notes, due April 15, 2032 | Vistra Operations Senior Unsecured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 1,000		1,000
Debt instrument, interest rate, stated percentage		6.875%
Equipment Financing Agreements | Other Debt
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently		$ 55		$ 55
Senior Secured Notes Due | Vistra Operations Senior Secured Notes | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, face amount	$ 2,000