Revenue - Summary of Disaggregates TEC Revenue by Major Source (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation Of Revenue [Line Items]
Total electric revenue	$ 672	$ 677	$ 1,220	$ 1,229
Total revenue	672	677	1,220	1,229
Residential [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	385	430	689	755
Commercial [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	177	201	332	371
Industrial [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	42	50	82	96
Regulatory Deferrals [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	(28)	(97)	(50)	(160)
Unbilled Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	24	21	27	24
Other [Member]
Disaggregation Of Revenue [Line Items]
Total electric revenue	$ 72	$ 72	$ 140	$ 143