Consolidated Statements of Capitalization - Capital Stock (Parenthetical) (Detail) (USD $)	Dec. 31, 2012
Preferred Stock Par Value [Member)
Preferred stock - par value	$ 1
Preferred stock, shares authorized	10,000,000
Preferred stock, shares outstanding	0
TAMPA ELECTRIC CO [Member] | Preferred Stock Par Value [Member)
Preferred stock - par value	$ 100
Preferred stock, shares authorized	1,500,000
Preferred stock, shares outstanding	0
TAMPA ELECTRIC CO [Member] | Preferred Stock No Par Value [Member]
Preferred stock, no par value	$ 0
Preferred stock, shares authorized	2,500,000
Preferred stock, shares outstanding	0
TAMPA ELECTRIC CO [Member] | Preference Stock No Par Value [Member]
Preferred stock, no par value	$ 0
Preferred stock, shares authorized	2,500,000
Preferred stock, shares outstanding	0