Consolidated Statements of Capitalization - Long-Term Debt - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, total	$ 2,604	$ 2,183
Unamortized debt discount, net	(7)	(3)
Debt issuance costs	(22)	(16)
Long-term debt, carrying amount	2,575	2,164
Less amount due within one year	0	304
Total long-term debt	2,575	1,860
Long-term debt, fair value	2,686	2,412
Level 1 [Member]
Debt Instrument [Line Items]
Long-term debt, fair value	0	55
Tampa Electric [Member]
Debt Instrument [Line Items]
Long-term debt, total	2,292	1,921
Long-term debt, carrying amount	$ 2,292
Tampa Electric [Member] \| 5.65% Refunding bonds [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	$ 0	54
Tampa Electric [Member] \| 6.10% Notes [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	$ 0	200
Tampa Electric [Member] \| 5.40% Notes [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	$ 232	232
Tampa Electric [Member] \| 2.60% Notes [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	$ 225	225
Tampa Electric [Member] \| 6.55% Notes [Member]
Debt Instrument [Line Items]
Due	2036
Long-term debt, total	$ 250	250
Tampa Electric [Member] \| 6.15% Notes [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	$ 190	190
Tampa Electric [Member] \| 4.10% Notes [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	$ 250	250
Tampa Electric [Member] \| 4.35% Notes [Member]
Debt Instrument [Line Items]
Due	2044
Long-term debt, total	$ 290	290
Tampa Electric [Member] \| 4.20% Notes [Member]
Debt Instrument [Line Items]
Due	2045
Long-term debt, total	$ 230	230
Tampa Electric [Member] \| 4.30% Notes [Member]
Debt Instrument [Line Items]
Due	2048
Long-term debt, total	$ 275	0
Tampa Electric [Member] \| 4.45% Notes [Member]
Debt Instrument [Line Items]
Due	2049
Long-term debt, total	$ 350	0
PGS [Member]
Debt Instrument [Line Items]
Long-term debt, total	312	262
Long-term debt, carrying amount	$ 312
PGS [Member] \| 6.10% Notes [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	$ 0	50
PGS [Member] \| 5.40% Notes [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	$ 47	47
PGS [Member] \| 2.60% Notes [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	$ 25	25
PGS [Member] \| 6.15% Notes [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	$ 60	60
PGS [Member] \| 4.10% Notes [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	$ 50	50
PGS [Member] \| 4.35% Notes [Member]
Debt Instrument [Line Items]
Due	2044
Long-term debt, total	$ 10	10
PGS [Member] \| 4.20% Notes [Member]
Debt Instrument [Line Items]
Due	2045
Long-term debt, total	$ 20	20
PGS [Member] \| 4.30% Notes [Member]
Debt Instrument [Line Items]
Due	2048
Long-term debt, total	$ 75	0
PGS [Member] \| 4.45% Notes [Member]
Debt Instrument [Line Items]
Due	2049
Long-term debt, total	$ 25	$ 0

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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