Long-Term Debt	9 Months Ended
Sep. 30, 2020
Debt Disclosure [Abstract]
Long-Term Debt	7. Long-Term Debt Fair Value of Long-Term Debt At September 30, 2020, TEC’s long-term debt, including the current portion, had a carrying amount of $2,872 million and an estimated fair market value of $3,585 million. At December 31, 2019, TEC’s total long-term debt, including the current portion, had a carrying amount of $2,869 million and an estimated fair market value of $3,335 million. The fair value of the debt securities is determined using Level 2 measurements (see Note 11 for information regarding the fair value hierarchy).

Long-Term Debt

9 Months Ended

Sep. 30, 2020

7. Long-Term Debt

Fair Value of Long-Term Debt

At September 30, 2020, TEC’s long-term debt, including the current portion, had a carrying amount of $2,872 million and an estimated fair market value of $3,585 million. At December 31, 2019, TEC’s total long-term debt, including the current portion, had a carrying amount of $2,869 million and an estimated fair market value of $3,335 million. The fair value of the debt securities is determined using Level 2 measurements (see Note 11 for information regarding the fair value hierarchy).