Short-Term Debt (Credit Facilities) (Details) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011		Dec. 31, 2010
Credit Facilities	$ 675.0		$ 675.0
Borrowings Outstanding	32.0	[1]	12.0	[1]
Letters of Credit Outstanding	0.7		7.4
Credit facility maturity date	May 9, 2012
Teco Energy Inc [Member] | 5 Year Facility [Member]
Credit Facilities	200.0	[2],[3]	200.0	[2],[3]
Borrowings Outstanding	25.0	[1],[2],[3]	0	[1],[2],[3]
Letters of Credit Outstanding	0	[2],[3]	6.7	[2],[3]
Tampa Electric Co [Member] | 5 Year Facility [Member]
Credit Facilities	325.0	[3]	325.0	[3]
Borrowings Outstanding	7.0	[1],[3]	5.0	[1],[3]
Letters of Credit Outstanding	0.7	[3]	0.7	[3]
Tampa Electric Co [Member] | 1 Year Accounts Receivable Facility [Member]
Credit Facilities	150.0		150.0
Borrowings Outstanding	0	[1]	7.0	[1]
Letters of Credit Outstanding	$ 0		$ 0
Tampa Electric Co [Member]
Credit facility maturity date	May 9, 2012

[1] Borrowings outstanding are reported as notes payable.

[2] TECO Finance is the borrower and TECO Energy is the guarantor of this facility.

[3] This 5-year facility matures May 9, 2012.