Acquisitions and Divestitures - Schedule of Acquired Contract Liabilities, Future Amortization Expense (Details) $ in Millions	Jun. 30, 2026 USD ($)
Estimated amortization of acquired contract liabilities
2028	$ 18
2029	29
2030	29
2031	24
2032	21
Thereafter	30
Total	$ 151

Acquired Contract Liabilities, Expected Amortization, After Year Five

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Acquired Fuel Supply Contract Liabilities, Expected Amortization

No definition available.

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Acquired Contract Liabilities, Expected Amortization, Year Five

No definition available.

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Acquired Contract Liabilities, Expected Amortization, Year Four

No definition available.

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Acquired Contract Liabilities, Expected Amortization, Year One

No definition available.

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Acquired Contract Liabilities, Expected Amortization, Year Three

No definition available.

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Acquired Contract Liabilities, Expected Amortization, Year Two

No definition available.

Name:	tln_AcquiredContractLiabilitiesExpectedAmortizationYearTwo
Namespace Prefix:	tln_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Acquired Fuel Supply Contract Liabilities, Expected Amortization

No definition available.

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