Significant Accounting Policies - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total cost	$ 12,520	$ 14,292
Total property, plant and equipment, net	10,228	11,644
Tampa Electric [Member]
Property Plant And Equipment [Line Items]
Less accumulated depreciation	(3,443)	(3,158)
Construction work in progress	1,151	949
PGS [Member]
Property Plant And Equipment [Line Items]
Less accumulated depreciation	0	(687)
Construction work in progress	0	248
Total property, plant and equipment, net		2,251
Electric Generation [Member]
Property Plant And Equipment [Line Items]
Total cost	6,732	6,300
Gas Transmission and Distribution [Member]
Property Plant And Equipment [Line Items]
Total cost	0	2,567
General Plant and Other [Member]
Property Plant And Equipment [Line Items]
Total cost	$ 997	1,020
Minimum [Member] | Electric Generation [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	10 years
Minimum [Member] | Gas Transmission and Distribution [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	15 years
Minimum [Member] | General Plant and Other [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	4 years
Maximum [Member] | Electric Generation [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	60 years
Maximum [Member] | Gas Transmission and Distribution [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	75 years
Maximum [Member] | General Plant and Other [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	60 years
Electric Transmission [Member]
Property Plant And Equipment [Line Items]
Total cost	$ 1,182	1,109
Electric Transmission [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	10 years
Electric Transmission [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	75 years
Electric Distribution [Member]
Property Plant And Equipment [Line Items]
Total cost	$ 3,609	$ 3,296
Electric Distribution [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	10 years
Electric Distribution [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives	60 years