Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 552	$ 691
Total interest charges	58	35
Net income	79	118
Total assets	12,273		$ 13,803
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	552	691
Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	0	0
Eliminations/Reclassifications [Member]
Segment Reporting Information [Line Items]
Total revenues		(2)
Total interest charges		0
Net income		0
Total assets	(647)		(732)
Eliminations/Reclassifications [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues		0
Eliminations/Reclassifications [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales		(2)
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	552	510
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	552	510
Total interest charges	58	30
Net income	79	88
Total assets	12,920		12,064
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	552	509
Tampa Electric [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	$ 0	1
PGS [Member]
Segment Reporting Information [Line Items]
Total revenues		183
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		183
Total interest charges		5
Net income		30
Total assets			$ 2,471
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues		182
PGS [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales		$ 1