Income Taxes - Schedule of Income Taxes Calculated on Income before Income Taxes and Provision for Income Taxes (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Effective tax rate	35.00%	35.00%	35.00%
Tampa Electric Company [Member]
Schedule Of Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Effective tax rate	35.00%	35.00%	35.00%