Short-Term Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended	0 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 24, 2015
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity	$ 900.0	$ 900.0
Credit facility maturity date	Dec. 17, 2018	Dec. 17, 2018
Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	0.87%	0.70%
Line of Credit Facility maximum borrowing capacity	475.0	475.0
Credit facility maturity date	Dec. 17, 2018	Dec. 17, 2018
Tampa Electric Company [Member] | 1-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility maximum borrowing capacity	$ 150.0	$ 150.0
Credit facility maturity date			Mar. 23, 2018
Credit Facility amendment date			Mar. 24, 2015
Tampa Electric Company [Member] | 1-year Accounts Receivable Facility [Member] | Before Amendment and Restatement
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	1.12%	1.16%
TECO Finance [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	1.12%	1.16%
New Mexico Gas Company [Member]
Line Of Credit Facility [Line Items]
Weighted-average interest rate	1.12%	1.16%
Minimum [Member] | Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage	0.125%
Maximum [Member] | Tampa Electric Company [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage	0.30%