Long-Term Debt	9 Months Ended
Sep. 30, 2025
Debt Disclosure [Abstract]
Long-Term Debt	7. Long-Term Debt Fair Value of Long-Term Debt At September 30, 2025, TEC’s long-term debt, including the current portion, had a carrying amount of $4,530 million and an estimated fair market value of $4,162 million. At December 31, 2024, long-term debt had a carrying amount of $3,935 million and an estimated fair market value of $3,431 million. The fair value of the debt securities is determined using Level 2 measurements. TEC 5.15% Notes due 2035 On March 6, 2025, TEC completed a sale of $600 million aggregate principal amount of 5.15% Notes due March 1, 2035 (the 2035 Notes). Prior to December 1, 2034, in the case of the 2035 Notes, TEC may redeem all or any part of such series of Notes at its option at a redemption price equal to the greater of (i) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the Treasury Rate plus 15 basis points less interest accrued to the date of redemption or (ii) 100% of the principal amount of the notes to be redeemed, plus, in either case, accrued and unpaid interest thereon to the redemption date. On or after December 1, 2034, TEC may redeem the 2035 Notes, in whole or in part, at any time and from time to time, at a redemption price equal to 100% of the principal amount of the notes being redeemed plus accrued and unpaid interest thereon to the redemption date. TEC used the net proceeds from this offering for the repayment of a portion of the borrowings outstanding under the 5-year credit facility as disclosed in Note 6.

Long-Term Debt

9 Months Ended

Sep. 30, 2025

7. Long-Term Debt

Fair Value of Long-Term Debt

At September 30, 2025, TEC’s long-term debt, including the current portion, had a carrying amount of $4,530 million and an estimated fair market value of $4,162 million. At December 31, 2024, long-term debt had a carrying amount of $3,935 million and an estimated fair market value of $3,431 million. The fair value of the debt securities is determined using Level 2 measurements.

TEC 5.15% Notes due 2035

On March 6, 2025, TEC completed a sale of $600 million aggregate principal amount of 5.15% Notes due March 1, 2035 (the 2035 Notes). Prior to December 1, 2034, in the case of the 2035 Notes, TEC may redeem all or any part of such series of Notes at its option at a redemption price equal to the greater of (i) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the Treasury Rate plus 15 basis points less interest accrued to the date of redemption or (ii) 100% of the principal amount of the notes to be redeemed, plus, in either case, accrued and unpaid interest thereon to the redemption date. On or after December 1, 2034, TEC may redeem the 2035 Notes, in whole or in part, at any time and from time to time, at a redemption price equal to 100% of the principal amount of the notes being redeemed plus accrued and unpaid interest thereon to the redemption date. TEC used the net proceeds from this offering for the repayment of a portion of the borrowings outstanding under the 5-year credit facility as disclosed in Note 6.

TAMPA ELECTRIC CO 10-Q