Regulatory - Additional Information (Detail)												1 Months Ended			3 Months Ended	12 Months Ended					60 Months Ended
	Oct. 12, 2021 USD ($)	Aug. 06, 2021 USD ($)	Aug. 03, 2021 USD ($)	Nov. 19, 2020 USD ($)	Aug. 18, 2020 USD ($)	Aug. 03, 2020 USD ($)	Apr. 27, 2020 USD ($)	Apr. 09, 2019 USD ($)	Dec. 28, 2017 USD ($)	Feb. 07, 2017	Sep. 06, 2013	Jan. 31, 2024 USD ($)	Jan. 31, 2023 USD ($)	Jan. 31, 2022 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2021 USD ($) Unit $ / Kwac	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016	Dec. 31, 2021 USD ($) $ / Kwac MW	Jun. 09, 2020 USD ($)	Dec. 31, 2018 USD ($)	Oct. 31, 2013 USD ($)
Public Utilities General Disclosures [Line Items]
Percentage of ROE																10.25%
Return on equity range																range of plus or minus 1%
Percentage change in ROE Percentage																1.00%
Allowed equity in the capital structure											54.00%
Federal statutory tax rate																4.50%	5.50%
Decrease in deferred income taxes offset to regulatory liability																$ 5,000,000
Utility plant, at original costs																14,189,000,000	$ 13,818,000,000				$ 14,189,000,000
Accumulated depreciation																$ 3,601,000,000	3,712,000,000				3,601,000,000
Number of units applied for recovery | Unit																3
Additional cost recovery from settlement agreement			$ 83,000,000
Storm restoration costs									$ 10,000,000
Regulatory assets																$ 1,002,000,000	485,000,000				1,002,000,000
O&M expense																566,000,000	542,000,000	$ 543,000,000
Regulatory liability																1,170,000,000	1,261,000,000				1,170,000,000
Provision for income taxes																80,000,000	82,000,000	77,000,000
Amount refundable on settlement								$ 12,000,000
Regulatory asset amortization ending period																			2020
Reduction in regulatory asset for amortization																10,000,000	18,000,000	(1,000,000)
Subsequent Event [Member]
Public Utilities General Disclosures [Line Items]
Additional cost recovery from settlement agreement														$ 169,000,000
Peoples Gas System [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE										10.75%
Allowed equity in the capital structure										54.70%
Reduction in annual base rates																		12,000,000
Regulatory assets																							$ 11,000,000
Reduction in annual depreciation rates																		10,000,000
PGS and OPC [Member]
Public Utilities General Disclosures [Line Items]
Allowed equity in the capital structure				54.70%
Increase in revenue				$ 34,000,000
Impact of tax reform through reduction in base revenue days				120 days
Accumulated depreciation				$ 34,000,000
Regulatory assets																			$ 32,000,000
Date new bottom of return on equity range will remain in effect																				Dec. 31, 2020
Regulatory asset amortization beginning period																			2016
Increase in annual base rate				58,000,000
Hurricanes [Member]
Public Utilities General Disclosures [Line Items]
Storm restoration preparation costs																10,000,000	10,000,000	$ 10,000,000
Storm Reserve [Member]
Public Utilities General Disclosures [Line Items]
Regulatory liability																46,000,000	48,000,000				46,000,000
Hurricane Irma [Member]
Public Utilities General Disclosures [Line Items]
Storm restoration costs															$ 102,000,000
Hurricane Irma [Member] | Storm Reserve [Member]
Public Utilities General Disclosures [Line Items]
Storm restoration costs															90,000,000
Hurricane Irma [Member] | Capital Expenditures [Member]
Public Utilities General Disclosures [Line Items]
Storm restoration costs															$ 9,000,000
Intangible Software Assets [Member]
Public Utilities General Disclosures [Line Items]
Accumulated amortization reserve surplus																						$ 16,000,000
Electric Utility Plant [Member]
Public Utilities General Disclosures [Line Items]
Utility plant, at original costs																$ 11,563,000,000	11,486,000,000				$ 11,563,000,000
Cast Iron and Bare Steel Replacement Rider [Member] | PGS and OPC [Member]
Public Utilities General Disclosures [Line Items]
Increase in revenue				$ 24,000,000
Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Settlement agreement, approval date		Aug. 06, 2021
Allowed equity in the capital structure		54.00%
Base rate adjustment amount		$ 123,000,000
Increase in revenue		$ 191,000,000
Settlement agreement number of subsequent years adjustments		2 years
Basis point increase applicable		0.25%
Additional attainable revenue under settlement agreement		$ 10,000,000
Changes in base rate under agreement		$ 0
Impact of tax reform through reduction in base revenue days		180 days
Settlement Agreement [Member] | Scenario Forecast [Member]
Public Utilities General Disclosures [Line Items]
Settlement agreement adjustment amount												$ 21,000,000	$ 90,000,000
Settlement Agreement [Member] | US Treasury Bond [Member]
Public Utilities General Disclosures [Line Items]
Calculating period		30 years
Determining period		6 months
Minimum [Member] | PGS and OPC [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE				8.90%
Base rate agreement frozen period				Jan. 01, 2021
Decrease bottom return on equity										11.75%
Minimum [Member] | Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE		9.00%
Base rate agreement frozen period		Jan. 01, 2022
Minimum [Member] | Settlement Agreement [Member] | US Treasury Bond [Member]
Public Utilities General Disclosures [Line Items]
ROE revenue basis point on yield rate		0.50%
Maximum [Member] | PGS and OPC [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE				11.00%
Base rate agreement frozen period				Dec. 31, 2023
Decrease bottom return on equity										9.25%
Maximum [Member] | Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE		11.00%
Base rate agreement frozen period		Dec. 31, 2024
Mid Point [Member] | PGS and OPC [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE				9.90%
Mid Point [Member] | Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Percentage of ROE		9.95%
Condition One [Member]
Public Utilities General Disclosures [Line Items]
ROE lower range limit																9.25%
Condition Two [Member]
Public Utilities General Disclosures [Line Items]
ROE lower range limit																11.25%
Solar Project Cost Recovery [Member]
Public Utilities General Disclosures [Line Items]
Settlement agreement, extended terms																four years through 2021
Settlement agreement, approval date																Nov. 06, 2017
Cost cap of project | $ / Kwac																1,500					1,500
Cost savings benefit percentage for projects below cost cap																75.00%
Solar generation capacity investments																$ 850,000,000					$ 850,000,000
Solar energy capacity | MW																					600
Estimated revenue requirements																104,000,000					$ 104,000,000
Investments in gas reserves																0					0
Solar Project Cost Recovery [Member] | Solar Base Rate Adjustments [Member]
Public Utilities General Disclosures [Line Items]
True-up amount returned to customers	$ 4,000,000				$ 5,000,000
Solar Project Cost Recovery [Member] | Effective September 2018 [Member]
Public Utilities General Disclosures [Line Items]
Estimated revenue requirements																24,000,000					24,000,000
Solar Project Cost Recovery [Member] | Effective January 2019 [Member]
Public Utilities General Disclosures [Line Items]
Estimated revenue requirements																46,000,000					46,000,000
Solar Project Cost Recovery [Member] | Effective January 2020 [Member]
Public Utilities General Disclosures [Line Items]
Estimated revenue requirements																26,000,000					26,000,000
Solar Project Cost Recovery [Member] | Effective January 2021 [Member]
Public Utilities General Disclosures [Line Items]
Estimated revenue requirements																$ 8,000,000					8,000,000
Solar Project Cost Recovery [Member] | Minimum [Member]
Public Utilities General Disclosures [Line Items]
Solar project investment term																2017
Solar Project Cost Recovery [Member] | Maximum [Member]
Public Utilities General Disclosures [Line Items]
Solar project investment term																2021
Retiring Assets [Member] | Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Cost recovery from settlement agreement		$ 68,000,000
Retiring Coal Generation Units and Meter Assets [Member] | Settlement Agreement [Member]
Public Utilities General Disclosures [Line Items]
Settlement agreement cost recovery period		15 years
Big Bend Modernization Project [Member]
Public Utilities General Disclosures [Line Items]
Energy generation capacity investments																$ 850,000,000					850,000,000
Investments in energy projects till date																$ 695,000,000					$ 695,000,000
Accumulated depreciation																	267,000,000
Settlement agreement recovery description																Tampa Electric’s Settlement Agreement provides recovery for the Big Bend modernization project in two phases. The first phase is a revenue increase to cover the costs of the assets in service during 2022, among other items. The remainder of the project costs will be recovered as part of the 2023 subsequent year adjustment.
Big Bend Modernization Project [Member] | Electric Utility Plant [Member]
Public Utilities General Disclosures [Line Items]
Utility plant, at original costs																	$ 636,000,000
Big Bend Modernization Project [Member] | Minimum [Member]
Public Utilities General Disclosures [Line Items]
Energy project investment term																2018
Big Bend Modernization Project [Member] | Maximum [Member]
Public Utilities General Disclosures [Line Items]
Energy project investment term																2023
Big Bend Coal Generation Assets [Member]
Public Utilities General Disclosures [Line Items]
Settlement agreement cost recovery period																15 years
Storm Protection Plan [Member]
Public Utilities General Disclosures [Line Items]
Cost recovery from settlement agreement						$ 39,000,000
Reduction in annual base rates							$ 15,000,000
Storm Restoration Cost Recovery [Member]
Public Utilities General Disclosures [Line Items]
Minimum cost recovery period																12 months
Replenishment reserve for recovery of cost																								$ 56,000,000
Storm Reserve [Member]
Public Utilities General Disclosures [Line Items]
Regulatory assets									$ 56,000,000