Revenue - Summary of Disaggregates TEC Revenue by Major Source (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation Of Revenue [Line Items]
Total electric revenue	$ 548	$ 552
Total revenue	548	552
Residential [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	304	325
Commercial [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	155	170
Industrial [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	40	46
Regulatory Deferrals [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	(23)	(63)
Unbilled Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	3	3
Other [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	$ 69	$ 71