Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Allowance for uncollectibles	$ 4.7	$ 4.2
Common equity, shares authorized	400,000,000	400,000,000
Common equity, par value	$ 1	$ 1
Common equity, shares outstanding	217,300,000	216,600,000
Tampa Electric Company [Member]
Allowance for uncollectibles	$ 2.0	$ 1.5
Common equity, shares authorized	25,000,000	25,000,000
Common equity, shares outstanding	10	10