Short-Term Debt - Additional Information (Detail) - USD ($)						12 Months Ended
	Dec. 31, 2015	Apr. 10, 2015	Mar. 24, 2015	Sep. 02, 2014	Dec. 17, 2013	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Jun. 24, 2013
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity	$ 900,000,000			$ 40,000,000		$ 900,000,000	$ 900,000,000
Senior unsecured bridge credit										$ 1,075,000,000
Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	0.70%					0.70%	0.89%
Line of Credit Facility maximum borrowing capacity	$ 475,000,000				$ 200,000,000	$ 475,000,000	$ 475,000,000
Interest rate description						TEC to borrow funds at an interest rate equal to a margin plus the higher of Citibank's prime rate, the federal funds rate plus 50 basis points, or the London interbank deposit rate plus 1.00%;
Increase of credit facility					175,000,000
Tampa Electric Company [Member] | Amended And Restated Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity					$ 325,000,000			$ 325,000,000
Basis spread on federal funds rate					0.50%
Tampa Electric Company [Member] | 1-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity	$ 150,000,000					$ 150,000,000
Credit facility maturity date			Mar. 23, 2018
Credit Facility amendment date			Mar. 24, 2015
Loan agreement program and liquidity fees	0.65%
Basis spread on federal funds rate			0.50%
Interest rate description						Pursuant to the Loan Agreement, TRC will pay program and liquidity fees, which total 65 basis points as of Dec. 31, 2015. Interest rates on the borrowings are based on prevailing asset-backed commercial paper rates, unless such rates are not available from conduit lenders, in which case the rates will be at an interest rate equal to, at TEC’s option, either the BTMU’s prime rate (or the federal funds rate plus 50 basis points, if higher) or a rate based on the London interbank deposit rate (if available) plus a margin
Tampa Electric Company [Member] | Before Amendment and Restatement [Member] | 1-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date			Apr. 14, 2015
TECO Energy [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	1.29%					1.29%	1.16%
Basis spread on federal funds rate					0.50%
Interest rate description						TECO Finance to borrow funds at an interest rate equal to the London interbank deposit rate plus a margin; (iv) as an alternative to the above interest rate, allows TECO Finance to borrow funds at an interest rate equal to a margin plus the higher of the JPMorgan Chase Bank's prime rate, the federal funds rate plus 50 basis points, or the London interbank deposit rate plus 1.00%;
TECO Energy [Member] | Revolving Credit Facility [Member]
Line Of Credit Facility [Line Items]
Maximum debt capitalization ratio									65.00%
TECO Finance [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	1.29%					1.29%	1.16%
Line of Credit Facility maximum borrowing capacity					$ 200,000,000
Increase of credit facility					100,000,000
Debt instrument maturity date		May 31, 2015
TECO Finance [Member] | Amended And Restated Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity								$ 300,000,000
New Mexico Gas Company [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	1.29%					1.29%	1.16%
New Mexico Gas Company [Member] | NMGC Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity					$ 125,000,000
Credit facility maturity date				Dec. 17, 2018
Basis spread on federal funds rate				0.50%
Interest rate description						as an alternative to the above interest rate, allows NMGC to borrow funds at an interest rate equal to a margin plus the higher of JPMorgan Chase Bank’s prime rate, the federal funds rate plus 50 basis points, or the London interbank deposit rate plus 1.00%;
New Mexico Gas Company [Member] | NMGC Credit Agreement [Member] | Letter of Credit [Member]
Line Of Credit Facility [Line Items]
Increase of credit facility				$ 75,000,000
TEC Receivables Company [Member] | 1-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Interest rate description						Pursuant to the Loan Agreement, TRC will pay program and liquidity fees, which total 65 basis points as of Dec. 31, 2015. Interest rates on the borrowings are based on prevailing asset-backed commercial paper rates, unless such rates are not available from conduit lenders, in which case the rates will be at an interest rate equal to, at TEC’s option, either the BTMU’s prime rate (or the federal funds rate plus 50 basis points, if higher) or a rate based on the London interbank deposit rate (if available) plus a margin.
Minimum [Member] | Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage						0.125%
Minimum [Member] | Tampa Electric Company [Member] | Amended And Restated Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Debt instrument maturity date					Oct. 25, 2016
Minimum [Member] | TECO Energy [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date					Oct. 25, 2016
Maximum [Member] | Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage						0.30%
Maximum [Member] | Tampa Electric Company [Member] | Amended And Restated Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Debt instrument maturity date					Dec. 17, 2018
Maximum [Member] | TECO Energy [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date					Dec. 17, 2018
Maximum [Member] | TECO Energy [Member] | Revolving Credit Facility [Member]
Line Of Credit Facility [Line Items]
Maximum debt capitalization ratio							70.00%