Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Allowance for uncollectibles	$ 2.1	$ 2.1
Common equity, shares authorized	400,000,000	400,000,000
Common equity, par value	$ 1	$ 1
Common equity, shares outstanding	235,300,000	234,900,000
Tampa Electric Company [Member]
Allowance for uncollectibles	$ 1.5	$ 1.4
Common equity, shares authorized	25,000,000	25,000,000
Common equity, shares outstanding	10	10