Regulatory - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended					9 Months Ended
	Feb. 01, 2012	Mar. 31, 2011	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Tampa Electric Company [Member]	Dec. 31, 2013 Tampa Electric Company [Member]	Sep. 30, 2014 Tampa Electric Company [Member] Transmission and Delivery Storm Reserve [Member]	Dec. 31, 2013 Tampa Electric Company [Member] Transmission and Delivery Storm Reserve [Member]
Application to increase base rate on normalized annual basis		$ 34,500,000
Increased Base Rate on Normalized Annual Basis	21,500,000
Monthly residential customer access fee increase proposal	9.59
Monthly residential customer access fee increased	11.50
Annual accrual storm damage reserve					8,000,000
Storm damage reserve			$ 793,000,000	$ 717,200,000	$ 688,000,000	$ 717,200,000	$ 56,100,000	$ 56,100,000
Storm damage cost recovery period							12 months