Short-Term Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		9 Months Ended					9 Months Ended			9 Months Ended			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]	Sep. 30, 2013 Revolving Credit Facility [Member]	Jun. 24, 2013 Revolving Credit Facility [Member]	Sep. 30, 2013 Revolving Credit Facility [Member] Maximum [Member]	Sep. 30, 2013 TECO ENERGY, INC. [Member]	Sep. 30, 2013 Tampa Electric Company [Member]	Dec. 31, 2012 Tampa Electric Company [Member]	Sep. 30, 2013 Tampa Electric Company [Member] 1-year Accounts Receivable Facility [Member]	Feb. 15, 2013 Tampa Electric Company [Member] 1-year Accounts Receivable Facility [Member]	Dec. 31, 2012 Tampa Electric Company [Member] 1-year Accounts Receivable Facility [Member]	Sep. 30, 2013 Tampa Electric Company [Member] Minimum [Member]	Sep. 30, 2013 Tampa Electric Company [Member] Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fees, percentage			0.125%	0.25%					0.525%		0.525%			0.125%	0.25%
Outstanding borrowings	$ 0	$ 0							$ 0	$ 0	$ 0		$ 0
Credit facility	$ 675.0	$ 675.0				$ 200.0			$ 475.0	$ 475.0	$ 150.0	$ 150.0	$ 150.0
Debt instrument maturity date									Feb. 14, 2014
Basis spread on federal funds rate									0.50%		0.50%
Amended maturity date of credit facility	Oct. 25, 2016							Oct. 25, 2016	Oct. 25, 2016
Normal capitalization ratio					0.65		0.70
Mortgage bonds issued by certain regulated significant subsidiaries maximum principal amount					66.67%