Employee Postretirement Benefits - Additional Information (Detail) - USD ($)			12 Months Ended
		Jan. 02, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Redemption frequency description			The redemption frequency of the funds ranges from daily to weekly and the redemption notice period ranges from 1 business day to 30 business days.
Percentage of qualified pension plan's actuarial value of assets			118.00%	129.22%
Employer contributions			$ 15,000,000	$ 17,000,000	$ 16,000,000
Employer contributions in next fiscal year			$ 13,000,000
Employer matching contribution percentage of eligible participant contribution		75.00%					70.00%
Description of defined contribution plan			Effective January 1, 2017, the employer matching contributions increased from 70% to 75% with an additional incentive match of up to 25% of eligible participant contributions based on the achievement of certain operating company financial goals.
Defined contribution plan cost recognized			$ 22,000,000	22,000,000	21,000,000
Defined benefit plan additional percentage of eligible compensation for matching contributions by employer			25.00%
Non-qualified SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets			$ 8,000,000	10,000,000
Unfunded [Member]
Defined Benefit Plan Disclosure [Line Items]
Commitments			0
Tampa Electric [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			4,000,000	7,000,000	10,000,000
Employer contributions			12,000,000	14,000,000	13,000,000
Employer contributions in next fiscal year			11,000,000
Defined contribution plan cost recognized			19,000,000	18,000,000	20,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			8,000,000	10,000,000	12,000,000
Defined benefit plan, assets			0	78,000,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			9,000,000	11,000,000	7,000,000
Defined benefit plan, assets			0	0
Other Postretirement Benefits [Member] | Tampa Electric [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			8,000,000	9,000,000	6,000,000
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			0	0	0
Benefits paid			2,000,000	1,000,000	1,000,000
Expected payment in next twelve months			5,000,000
Non Elective Employer Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan cost recognized			10,000,000	10,000,000	9,000,000
TECO Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation of defined benefit pension plans			$ 634,000,000	819,000,000
Percentage of defined benefit plan's actual loss			23.50%
Defined contribution plan, employer match percentage			6.00%
Employer matching contribution percentage of eligible participant contribution			75.00%
TECO Energy [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			$ 9,000,000	12,000,000	16,000,000
Settlement charge			2,000,000	0	0	[1]
Commitments			666,000,000	850,000,000	919,000,000
Employer contributions			18,000,000	21,000,000
TECO Energy [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	[2]		8,000,000	9,000,000	6,000,000
Settlement charge	[2]		0	0	0
Commitments	[2]		142,000,000	200,000,000	$ 212,000,000
Employer contributions	[2]		0	$ 0
Employer contributions in next fiscal year			12,000,000
TECO Energy [Member] | Other Postretirement Benefits Florida-Based Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other postretirement benefit plans service benefit to be amortized from regulatory assets in next fiscal year			$ 0

[1] Represents TECO Energy’s SERP and Restoration settlement charges as a result of the retirement of certain executives. These charges did impact TEC’s financial statements.

[2] Represents amounts for TECO Energy’s Florida-based other postretirement benefit plan