Debt, Credit Facilities and Financings - Narrative (Details) $ in Thousands	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2025 USD ($)	Jun. 30, 2025 USD ($)	May 31, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Jul. 31, 2025 USD ($)	May 31, 2025 USD ($)	May 20, 2025 USD ($)	Apr. 01, 2025 USD ($)	Jul. 31, 2024 USD ($)
Debt Instrument [Line Items]
Facility Limit					$ 9,134,000		$ 9,134,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					3,944,000		3,944,000
Total long-term debt, including amounts due currently					15,988,000		15,988,000		$ 16,298,000
Borrowings under Revolving Credit Facility							150,000	$ 50,000
Accounts receivable financing					$ 1,225,000		1,225,000		750,000
Accounts receivable repurchase facility, term														1 month
Redeemable noncontrolling interest, payments		$ 80,000
Redeemable noncontrolling interest, principal payment		41,000					41,000	0
Redeemable noncontrolling interest, interest payment		39,000
Vistra Vision
Debt Instrument [Line Items]
Forward repurchase obligation to be paid							$ 1,314,000		$ 1,335,000
Vistra Vision | Measurement Input, Discount Rate
Debt Instrument [Line Items]
Noncontrolling interest, discount rate					0.06		0.06		0.06
BCOP Credit Facility
Debt Instrument [Line Items]
Facility Limit					$ 791,000		$ 791,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					791,000		791,000
Alternate Letter Of Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Facility Limit					500,000		500,000
Letters of credit outstanding					500,000		500,000
Line of credit facility, increase (decrease), net			$ 500,000
Alternate Letter Of Credit Facility | Letter of Credit | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility commitment fee amount	$ 800,000
Accounts Receivable Securitization Program
Debt Instrument [Line Items]
Accounts receivable financing					1,100,000		1,100,000		$ 750,000
Accounts receivable securitization program, gross trade accounts receivable held by special purpose subsidiary					1,764,000		1,764,000
Accounts Receivable Securitization Program | Maximum
Debt Instrument [Line Items]
Account receivable securitization program, total borrowing capacity		$ 1,000,000								$ 1,100,000
Repurchase Facility
Debt Instrument [Line Items]
Accounts receivable repurchase facility, maximum borrowing capacity														$ 125,000
Accounts receivable repurchase facility, amounts borrowed					125,000		125,000		0
Vistra Operations Company LLC | Vistra Corp.
Debt Instrument [Line Items]
Maximum allowable distribution to parent company by consolidated subsidiary without consent					10,900,000		10,900,000
Dividends paid					350,000	$ 515,000	1,275,000	$ 1,505,000
Line of Credit
Debt Instrument [Line Items]
Facility Limit					5,896,000		5,896,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					2,456,000		2,456,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Facility Limit					3,440,000		3,440,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					0		0
Line of Credit | Term Loan B-3 Facility
Debt Instrument [Line Items]
Facility Limit					2,456,000		2,456,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					$ 2,456,000		$ 2,456,000
Line of Credit | BCOP Credit Facility | Secured Debt
Debt Instrument [Line Items]
Debt, weighted average interest rate					5.648%		5.648%
Line of Credit | Construction/Term Loan Commitments | Secured Debt
Debt Instrument [Line Items]
Facility Limit									528,000
Line of Credit | Vistra Zero Project-Level Credit Agreement | Secured Debt
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							2.00%
Debt, weighted average interest rate					6.16%		6.16%
Debt instrument, face amount				$ 700,000
Borrowings under Revolving Credit Facility				$ 690,000
Line of Credit | Vistra Operations Company LLC
Debt Instrument [Line Items]
Facility Limit					$ 5,896,000		$ 5,896,000
Collateral suspension provision effective date, grace period, number of days							60 days
Debt instrument, interest rate during period							5.21%	5.52%
Line of Credit | Vistra Operations Company LLC | Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							1.725%
Debt instrument, fee on undrawn amounts							0.270
Debt instrument, interest rate, stated percentage					1.725%		1.725%
Line of Credit | Vistra Operations Company LLC | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							1.25%
Debt instrument, fee on undrawn amounts							0.175
Line of Credit | Vistra Operations Company LLC | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							2.00%
Debt instrument, fee on undrawn amounts							0.350
Line of Credit | Vistra Operations Company LLC | Term Loan B-3 Facility
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							1.75%
Line of credit facility, interest rate at period end					5.91%		5.91%
Debt instrument, periodic payment							$ 6,250
Revolving Credit Facility | Vistra Operations Commodity-Linked Facility
Debt Instrument [Line Items]
Facility Limit					$ 1,750,000		1,750,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					0		0
Revolving Credit Facility | Vistra Zero Term Loan B Facility
Debt Instrument [Line Items]
Facility Limit					697,000		697,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					697,000		$ 697,000
Revolving Credit Facility | Vistra Operations Company LLC | Vistra Operations Commodity-Linked Facility
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							1.725%
Debt instrument, fee on undrawn amounts							0.270
Line of credit facility, borrowing base capacity limit					644,000		$ 644,000
Borrowings outstanding					0		$ 0
Revolving Credit Facility | Vistra Operations Company LLC | Vistra Operations Commodity-Linked Facility | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							1.25%
Debt instrument, fee on undrawn amounts							0.175
Revolving Credit Facility | Vistra Operations Company LLC | Vistra Operations Commodity-Linked Facility | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate							2.00%
Debt instrument, fee on undrawn amounts							0.350
Line of credit facility, potential borrowing capacity, subject to ability to obtain additional commitments					$ 3,000,000		$ 3,000,000
Bridge Loans
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					1.625%		1.625%
Bridge Loans | BCOP Credit Facility
Debt Instrument [Line Items]
Facility Limit					$ 367,000		$ 367,000
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					367,000		367,000
Total long-term debt, including amounts due currently					367,000		367,000		367,000
Bridge Loans | BCOP Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)	106,000
Bridge Loans | BCOP Credit Facility | Oak Hill
Debt Instrument [Line Items]
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					106,000		106,000
Bridge Loans | BCOP Credit Facility | Pulaski
Debt Instrument [Line Items]
Cash Borrowings (Long-Term Debt, Including Amounts Due Currently)					$ 261,000		$ 261,000
Letter of Credit
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					2.00%		2.00%
Letter of Credit | BCOP Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding									29,000
Letter of Credit | Baldwin Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount													$ 7,000
Letter of Credit | Coffeen Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount													7,000
Letter of Credit | Vistra Operations Company LLC | Secured Letter of Credit Facilities
Debt Instrument [Line Items]
Letters of credit outstanding					$ 1,301,000		$ 1,301,000
Term Loan
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					2.00%		2.00%
Debt, weighted average interest rate					6.03%		6.03%
Term loan period (in years)							20 years
Term Loan | Baldwin Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount													75,000
Term Loan | Coffeen Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount													$ 46,000
Construction Term Loans Converted to Term Loan Due Dec 2029 | BCOP Credit Facility
Debt Instrument [Line Items]
Facility Limit												$ 88,000
Construction Loan Converted to Term Loan Due Dec 2026 | BCOP Credit Facility
Debt Instrument [Line Items]
Facility Limit					$ 216,000		$ 216,000
Construction Loans
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					1.875%		1.875%
Vistra Operations Senior Secured Notes
Debt Instrument [Line Items]
Total long-term debt, including amounts due currently					$ 4,400,000		$ 4,400,000		5,144,000
Vistra Operations Senior Secured Notes | Subsequent Event
Debt Instrument [Line Items]
Facility Limit	100,000
Vistra Operations Senior Secured Notes | 5.125% Senior Secured Notes, due May 13, 2025
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					5.125%		5.125%				5.125%
Total long-term debt, including amounts due currently					$ 0		$ 0		$ 744,000
Debt instrument, face amount											$ 744,000
Vistra Operations Senior Secured Notes | Senior Secured Notes Due | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, face amount	$ 2,000,000
Vistra Operations Senior Secured Notes | 4.300% Senior Secured Notes Due 2028 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.30%
Debt instrument, face amount	$ 750,000
Vistra Operations Senior Secured Notes | 4.600% Senior Secured Notes Due 2030 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.60%
Debt instrument, face amount	$ 500,000
Vistra Operations Senior Secured Notes | 5.250% Senior Secured Notes Due 2035 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.25%
Debt instrument, face amount	$ 750,000
Vistra Operations Senior Secured Notes | 5.500% Senior Secured Notes Due 2026 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.50%
Debt instrument, face amount	$ 1,000,000
Revenue Bonds
Debt Instrument [Line Items]
Debt instrument, face amount					$ 431,000		$ 431,000