Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 912	$ 747	$ 2,424	$ 2,000
Total interest charges	44	32	117	99
Net income	169	149	432	362
Total assets	13,452		13,452		$ 12,196
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	912	747	2,424	2,000
Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	0	0	0	0
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	(2)	(2)	(6)	(5)
Total interest charges	0	0	0	0
Net income	0	0	0	0
Total assets	(752)		(752)		(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)	(2)	(6)	(5)
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	753	634	1,926	1,613
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	753	634	1,926	1,613
Total interest charges	37	27	99	84
Net income	153	134	367	302
Total assets	11,811		11,811		10,650
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	752	633	1,923	1,610
Tampa Electric [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	1	1	3	3
PGS [Member]
Segment Reporting Information [Line Items]
Total revenues	161	115	504	392
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	161	115	504	392
Total interest charges	7	5	18	15
Net income	16	15	65	60
Total assets	2,393		2,393		$ 2,209
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	160	114	501	390
PGS [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Intracompany sales	$ 1	$ 1	$ 3	$ 2