Income Taxes - Schedule of Income Taxes Calculated on Income before Income Taxes and Provision for Income Taxes (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Statutory tax rate	35.00%	35.00%	35.00%
TAMPA ELECTRIC CO [Member]
Schedule Of Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Statutory tax rate	35.00%	35.00%	35.00%