Consolidated Statements of Capitalization - Capital Stock (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Common equity, shares authorized	400,000,000	400,000,000	400,000,000	400,000,000
Capital Stock Outstanding December 31, Shares	217,300,000	216,600,000	217,300,000	216,600,000
Cash Dividends Paid Per Share	$ 0.220	$ 0.220	$ 0.88	$ 0.88
Cash Dividends Paid			$ 191.2	$ 190.4
Tampa Electric Company [Member]
Common equity, shares authorized	25,000,000	25,000,000	25,000,000	25,000,000
Current Redemption on Price
Capital Stock Outstanding December 31, Shares	10	10	10	10
Capital Stock Outstanding December 31, Amount	2,030.4	1,970.4	2,030.4	1,970.4
Cash Dividends Paid Per Share
Cash Dividends Paid			$ 222.1	$ 228.3