Consolidated Statements of Capitalization - Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term debt, total	$ 2,923.8	$ 2,975.4
Long-term debt, carrying amount	2,921.1	2,972.7
Unamortized debt discount, net	(2.7)	(2.7)
Less amount due within one year	83.3	0
Total long-term debt	2,837.8	2,972.7
Long-Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt, total	1,880.8	1,932.6
Long-term debt, carrying amount	1,882.6	1,934.2
Total long-term debt	1,797.5	1,932.6
PGS [Member]
Debt Instrument [Line Items]
Long-term debt, total	231.7
PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt, total	231.7	231.7
6.1% Notes [Member] | PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	50.0	50.0
5.4% Notes [Member] | PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	46.7	46.7
2.6% Notes [Member] | PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	25.0	25.0
6.15% Notes [Member] | PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	60.0	60.0
4.1% Notes [Member]
Debt Instrument [Line Items]
Due	2042
4.1% Notes [Member] | PGS [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	50.0	50.0
Tampa Electric Company [Member]
Debt Instrument [Line Items]
Long-term debt, total	1,650.9	1,702.5
Less amount due within one year	83.3	0
Total long-term debt	1,797.5	1,932.6
Tampa Electric Company [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt, total	1,650.9	1,702.5
Unamortized debt discount, net	(1.8)	(1.6)
Less amount due within one year	83.3	0
Long-term debt, fair value	2,042.0	2,271.9
Tampa Electric Company [Member] | Long-Term Debt [Member] | Carrying Amount [Member]
Debt Instrument [Line Items]
Long-term debt, carrying amount	1,880.8	1,932.6
Tampa Electric Company [Member] | Variable rate bonds repurchased in 2008 Due To 2020 [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2020
Long-term debt, total	0	0
Tampa Electric Company [Member] | 5.65% Refunding bonds [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	54.2	54.2
Tampa Electric Company [Member] | 5.65% Refunding bonds [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	54.2	54.2
Tampa Electric Company [Member] | 5.15% Refunding bonds [Member]
Debt Instrument [Line Items]
Due	2025
Long-term debt, total	0	51.6
Tampa Electric Company [Member] | 5.15% Refunding bonds [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2025
Long-term debt, total	0	51.6
Tampa Electric Company [Member] | 1.5% term rate bonds repurchased in 2011 [Member]
Debt Instrument [Line Items]
Due	2030
Long-term debt, total	0	0
Tampa Electric Company [Member] | 1.5% term rate bonds repurchased in 2011 [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2030
Long-term debt, total	0	0
Tampa Electric Company [Member] | 5.0% Refunding bonds [Member]
Debt Instrument [Line Items]
Due	2034
Long-term debt, total	0	0
Tampa Electric Company [Member] | 5.0% Refunding bonds [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2034
Long-term debt, total	0	0
Tampa Electric Company [Member] | 6.25% Notes [Member]
Debt Instrument [Line Items]
Maturity range start	2014
Long-term debt, total	250.0	250.0
Tampa Electric Company [Member] | 6.25% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2016
Maturity range start	2014
Long-term debt, total	250.0	250.0
Tampa Electric Company [Member] | 6.1% Notes [Member]
Debt Instrument [Line Items]
Long-term debt, total	200.0	200.0
Tampa Electric Company [Member] | 6.1% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	200.0	200.0
Tampa Electric Company [Member] | 5.4% Notes [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	231.7	231.7
Tampa Electric Company [Member] | 5.4% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	231.7	231.7
Tampa Electric Company [Member] | 2.6% Notes [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	225.0	225.0
Tampa Electric Company [Member] | 2.6% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	225.0	225.0
Tampa Electric Company [Member] | 6.55% Notes [Member]
Debt Instrument [Line Items]
Due	2036
Long-term debt, total	250.0	250.0
Tampa Electric Company [Member] | 6.55% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2036
Long-term debt, total	250.0	250.0
Tampa Electric Company [Member] | 6.15% Notes [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	190.0	190.0
Tampa Electric Company [Member] | 6.15% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	190.0	190.0
Tampa Electric Company [Member] | 4.1% Notes [Member]
Debt Instrument [Line Items]
Long-term debt, total	250.0	250.0
Tampa Electric Company [Member] | 4.1% Notes [Member] | Long-Term Debt [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	$ 250.0	$ 250.0