Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 821	$ 654	$ 1,512	$ 1,253
Total interest charges	38	34	73	67
Net income	145	121	263	213
Total assets	12,864		12,864		$ 12,196
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	821	654	1,512	1,253
Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	0	0	0	0
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	(2)	(1)	(4)	(4)
Total interest charges	0	0	0	0
Net income	0	0	0	0
Total assets	(706)		(706)		(663)
Eliminations [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Eliminations [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	(2)	(1)	(4)	(4)
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	663	532	1,173	979
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	663	532	1,173	979
Total interest charges	32	29	62	57
Net income	126	102	214	167
Total assets	11,234		11,234		10,650
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	662	531	1,171	977
Tampa Electric [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	1	1	2	2
PGS [Member]
Segment Reporting Information [Line Items]
Total revenues	160	123	343	278
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	160	123	343	278
Total interest charges	6	5	11	10
Net income	19	19	49	46
Total assets	2,336		2,336		$ 2,209
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	159	123	341	276
PGS [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	$ 1	$ 0	$ 2	$ 2