Regulatory - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	Feb. 28, 2013	Sep. 30, 2013	Apr. 05, 2013	Dec. 31, 2012
Percentage of return on equity		11.25%
Allowed equity in the capital structure		54.00%
Period of average base rate		13 months
Revenue due to average base rate		$ 3,400,000,000
Increase in revenue by modification in base rate		33,500,000
Additional Revenue generated from increase in service charge			134,800,000
Return on equity maximum range	11.25%
Potential increase in ROE		10.25%
Return on equity range		Range of plus or minus 1%
Amortization period for computer software under regulatory requirement description		Tampa Electric will begin using a 15-year amortization period for all computer software
Annual accrual storm damage reserve		8,000,000
Storm damage reserve		55,400,000		50,400,000
Condition One [Member]
ROE lower range limit		9.25%
ROE upper range limit		11.25%
Condition Two [Member]
ROE lower range limit		9.50%
ROE upper range limit		11.50%
November 1, 2013 [Member]
Additional Revenue generated from increase in service charge		57,500,000
November 1, 2014
Additional Revenue generated from increase in service charge		7,500,000
November 1, 2015
Additional Revenue generated from increase in service charge		5,000,000
January 1,2017
Additional Revenue generated from increase in service charge		110,000,000
Transmission and Delivery Storm Reserve [Member]
Storm damage cost recovery period		12 months
Tampa Electric Company [Member]
Percentage of return on equity		11.25%
Allowed equity in the capital structure		54.00%
Period of average base rate		13 months
Revenue due to average base rate		3,400,000,000
Increase in revenue by modification in base rate		33,500,000
Additional Revenue generated from increase in service charge			134,800,000
Return on equity maximum range	11.25%
Potential increase in ROE		10.25%
Return on equity range		Range of plus or minus 1%
Amortization period for computer software under regulatory requirement description		Tampa Electric will begin using a 15-year amortization period for all computer software
Annual accrual storm damage reserve		8,000,000
Storm damage reserve		55,400,000		50,400,000
Tampa Electric Company [Member] | Condition One [Member]
ROE lower range limit		9.25%
ROE upper range limit		11.25%
Tampa Electric Company [Member] | Condition Two [Member]
ROE lower range limit		9.50%
ROE upper range limit		11.50%
Tampa Electric Company [Member] | November 1, 2013 [Member]
Additional Revenue generated from increase in service charge		57,500,000
Tampa Electric Company [Member] | November 1, 2014
Additional Revenue generated from increase in service charge		7,500,000
Tampa Electric Company [Member] | November 1, 2015
Additional Revenue generated from increase in service charge		5,000,000
Tampa Electric Company [Member] | January 1,2017
Additional Revenue generated from increase in service charge		110,000,000
Tampa Electric Company [Member] | Transmission and Delivery Storm Reserve [Member]
Storm damage cost recovery period		12 months
Maximum [Member]
Higher Revenue Requirements		104,000,000
Return on equity maximum range	12.25%
Potential increase in ROE		10.50%
Maximum [Member] | Tampa Electric Company [Member]
Higher Revenue Requirements		$ 104,000,000
Return on equity maximum range	12.25%
Potential increase in ROE		10.50%
Minimum [Member]
Return on equity maximum range	10.25%
Minimum [Member] | Tampa Electric Company [Member]
Return on equity maximum range	10.25%