Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 2,637	$ 3,169	$ 2,695
Depreciation and amortization	422	436	430
Interest income from affiliates	38	0	0
Total interest charges	239	167	130
Provision for income taxes	87	121	80
Net income	466	540	446
Total assets	11,831	13,803	12,196
Capital expenditures	1,294	1,427	1,397
Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	2,637	3,169	2,695
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues		(10)	(7)
Depreciation and amortization		0	0
Total interest charges		0	0
Provision for income taxes		0	0
Net income		0	0
Total assets		(732)	(663)
Capital expenditures		0	0
Eliminations [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues		(10)	(7)
Eliminations [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues		0	0
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	2,637	2,523	2,174
Depreciation and amortization	422	389	374
Interest income from affiliates	38
Total interest charges	239	142	110
Provision for income taxes	87	94	57
Net income	466	458	369
Total assets	11,831	12,064	10,650
Capital expenditures	1,294	1,099	1,081
Tampa Electric [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues	0	4	4
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 2,637	2,519	2,170
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		656	528
Depreciation and amortization		47	56
Total interest charges		25	20
Provision for income taxes		27	23
Net income		82	77
Total assets		2,471	2,209
Capital expenditures		328	316
PGS [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues		6	3
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues		$ 650	$ 525