Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 2,695	$ 2,272	$ 2,404
Depreciation and amortization	430	384	377
Total interest charges	130	130	134
Provision for income taxes	80	82	77
Net income	446	424	370
Total assets	12,196	11,048	10,007
Capital expenditures	1,397	1,361	1,283
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	2,695	2,272	2,404
Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0	0
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	(7)	(10)	(22)
Depreciation and amortization	0	0	0
Total interest charges	0	0	0
Provision for income taxes	0	0	0
Net income	0	0	0
Total assets	(663)	(653)	(593)
Capital expenditures	0	0	0
Eliminations [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0
Eliminations [Member] | Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	(7)	(10)	(22)
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	2,174	1,849	1,965
Tampa Electric [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	2,174	1,849	1,965
Depreciation and amortization	374	339	336
Total interest charges	110	113	117
Provision for income taxes	57	66	59
Net income	369	372	316
Total assets	10,650	9,800	9,007
Capital expenditures	1,081	1,028	1,055
Tampa Electric [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	2,170	1,845	1,961
Tampa Electric [Member] | Operating Segments [Member] | Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	4	4	4
PGS [Member]
Segment Reporting Information [Line Items]
Total revenues	528	433	461
PGS [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	528	433	461
Depreciation and amortization	56	45	41
Total interest charges	20	17	17
Provision for income taxes	23	16	18
Net income	77	52	54
Total assets	2,209	1,901	1,593
Capital expenditures	316	333	228
PGS [Member] | Operating Segments [Member] | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	525	427	443
PGS [Member] | Operating Segments [Member] | Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	$ 3	$ 6	$ 18