Short-Term Debt (Credit Facilities) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Line of Credit Facility [Line Items]
Credit	$ 675.0		$ 675.0
Borrowings Outstanding	20.0	[1]	0	[1]
Letters of Credit	0.7		0.7
Credit facility maturity date	Oct. 25, 2016
Tampa Electric Co [Member]
Line of Credit Facility [Line Items]
Credit	475.0		475.0
Borrowings Outstanding	0	[1]	0	[1]
Letters of Credit	0.7		0.7
Tampa Electric Co [Member] | 5-Year Facility [Member]
Line of Credit Facility [Line Items]
Credit	325.0	[1],[2],[3]	325.0	[1],[2],[3]
Borrowings Outstanding	0	[1],[2],[3]	0	[1],[2],[3]
Letters of Credit	0.7	[1],[2],[3]	0.7	[1],[2],[3]
Tampa Electric Co [Member] | 1-Year Accounts Receivable Facility [Member]
Line of Credit Facility [Line Items]
Credit	150.0		150.0
Borrowings Outstanding	0	[1]	0	[1]
Letters of Credit	0		0
TECO Energy [Member] | 5-Year Facility [Member]
Line of Credit Facility [Line Items]
Credit	200.0	[3],[4]	200.0	[3],[4]
Borrowings Outstanding	20.0	[1],[3],[4]	0	[1],[3],[4]
Letters of Credit	$ 0	[3],[4]	$ 0	[3],[4]

[1] Borrowings outstanding are reported as notes payable.

[2] Changes in OCI and AOCI are reported in after-tax dollars.

[3] This 5-year facility matures Oct. 25, 2016.

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