Preferred Stock - Additional Information (Detail)	Dec. 31, 2015 $ / shares shares
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, par value | $ / shares	$ 1
Preferred Stock Par Value [Member]
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, shares authorized	10,000,000
Preferred stock, shares outstanding	0
Tampa Electric Company [Member]
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, par value | $ / shares	$ 100
Preferred stock, no par value | $ / shares
Tampa Electric Company [Member] | Preferred Stock Par Value [Member]
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, shares authorized	1,500,000
Preferred stock, shares outstanding	0
Tampa Electric Company [Member] | Preferred Stock No Par Value [Member]
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, shares authorized	2,500,000
Preferred stock, shares outstanding	0
Tampa Electric Company [Member] | Preference Stock (Subordinated Preferred Stock) Of Tampa Electric - No Par [Member]
Authorized Classes Of Cumulative Preferred And Preference Stocks [Line Items]
Preferred stock, no par value | $ / shares
Preferred stock, shares authorized	2,500,000
Preferred stock, shares outstanding	0