Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 2,526	$ 2,637	$ 3,169
Fuel	517	605	676
Purchased power	105	78	151
Cost of natural gas sold	0	0	257
Operations & maintenance, excluding FPSC-approved regulatory deferrals	372	358	478
Operations & maintenance related to FPSC-approved regulatory deferrals	173	237	141
Operations & maintenance	545	595	619
Depreciation and amortization	454	422	436
Interest income from affiliates	0	(38)	0
Other segment items	176	183	202
Total interest charges	193	239	167
Provision for income taxes	68	87	121
Net Income (Loss)	468	466	540
Total assets	13,107	11,831	13,803
Capital expenditures	1,422	1,294	1,427
Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues			0
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	2,526	2,637	3,169
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues			(10)
Fuel			(5)
Purchased power			0
Cost of natural gas sold			0
Operations & maintenance, excluding FPSC-approved regulatory deferrals			(4)
Operations & maintenance related to FPSC-approved regulatory deferrals			0
Depreciation and amortization			0
Other segment items			(1)
Total interest charges			0
Provision for income taxes			0
Net Income (Loss)			0
Total assets			(732)
Capital expenditures			0
Eliminations [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues			(10)
Eliminations [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues			0
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	2,526	2,637	2,523
Fuel	517	605	681
Purchased power	105	78	151
Cost of natural gas sold			0
Operations & maintenance, excluding FPSC-approved regulatory deferrals	372	358	353
Operations & maintenance related to FPSC-approved regulatory deferrals	173	237	106
Depreciation and amortization	454	422	389
Interest income from affiliates		(38)
Other segment items	176	183	149
Total interest charges	193	239	142
Provision for income taxes	68	87	94
Net Income (Loss)	468	466	458
Total assets	13,107	11,831	12,064
Capital expenditures	1,422	1,294	1,099
Tampa Electric [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues			4
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 2,526	$ 2,637	2,519
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues			656
Fuel			0
Purchased power			0
Cost of natural gas sold			257
Operations & maintenance, excluding FPSC-approved regulatory deferrals			129
Operations & maintenance related to FPSC-approved regulatory deferrals			35
Depreciation and amortization			47
Other segment items			54
Total interest charges			25
Provision for income taxes			27
Net Income (Loss)			82
Total assets			2,471
Capital expenditures			328
PGS [Member] | Operating Segments [Member] | Intracompany Sales [Member]
Segment Reporting Information [Line Items]
Total revenues			6
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues			$ 650