Long-Term Debt - Schedule of Long-Term Debt Outstanding (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term debt, total	$ 2,975.4	$ 3,075.8
Unamortized debt discount, net	(2.7)	(2.4)
Long-term debt, carrying amount	2,972.7	3,073.4
Less amount due within one year	0	386.1
Total long-term debt	2,972.7	2,687.3
Teco Finance [Member]
Debt Instrument [Line Items]
Long-term debt, total	1,041.2	1,041.2
Tampa Electric [Member]
Debt Instrument [Line Items]
Long-term debt, total	1,702.5	1,768.9
PGS [Member]
Debt Instrument [Line Items]
Long-term debt, total	231.7	223.4
6.75% Notes [Member] | Teco Energy [Member]
Debt Instrument [Line Items]
Due	2015
Long-term debt, total	0	8.8
6.75% Notes [Member] | Teco Finance [Member]
Debt Instrument [Line Items]
Due	2015
Long-term debt, total	191.2	191.2
4.00% Notes [Member] | Teco Finance [Member]
Debt Instrument [Line Items]
Due	2016
Long-term debt, total	250.0	250.0
6.752% Notes [Member] | Teco Finance [Member]
Debt Instrument [Line Items]
Due	2017
Long-term debt, total	300.0	300.0
5.15% Notes [Member] | Teco Finance [Member]
Debt Instrument [Line Items]
Due	2020
Long-term debt, total	300.0	300.0
5.1% Refunding bonds [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2013
Long-term debt, total	0	60.7
5.65% Refunding bonds [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	54.2	54.2
Variable Rate Bonds Repurchased In 2008 [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2020
Long-term debt, total	0	0
5.5% Refunding bonds [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2023
Long-term debt, total	0	86.4
5.15% Refunding bonds [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2025
Long-term debt, total	51.6	51.6
1.5% term rate bonds repurchased in 2011 [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2030
Long-term debt, total	0	0
5.0% Refunding bonds [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2034
Long-term debt, total	0	86.0
6.875% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2012
Long-term debt, total	0	99.6
6.875% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2012
Long-term debt, total	0	19.0
6.375% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2012
Long-term debt, total	0	208.7
6.375% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2012
Long-term debt, total	0	44.3
6.25% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Maturity range start	2014
Due	2016
Long-term debt, total	250.0	250.0
6.1% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	200.0	200.0
6.1% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2018
Long-term debt, total	50.0	50.0
5.4% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	231.7	231.7
5.4% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2021
Long-term debt, total	46.7	46.7
2.6% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	225.0	0
2.6% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2022
Long-term debt, total	25.0	0
6.55% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2036
Long-term debt, total	250.0	250.0
6.15% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	190.0	190.0
6.15% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2037
Long-term debt, total	60.0	60.0
4.1% Notes [Member] | Tampa Electric [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	250.0	0
4.1% Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2042
Long-term debt, total	50.0	0
8.00% Senior Notes [Member] | PGS [Member]
Debt Instrument [Line Items]
Due	2012
Long-term debt, total	0	3.4
3.00% Notes [Member] | TECO Guatemala [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 0	$ 33.5