Regulatory - Schedule of Regulatory Assets and Regulatory Liabilities (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2015
Schedule Of Regulatory Assets And Liabilities [Line Items]
Amortization period	Amortized over a 5-year
Tampa Electric Company [Member]
Schedule Of Regulatory Assets And Liabilities [Line Items]
Amortization period	Amortized over a 5-year

The amortization period for recovery of the individual regulatory noncurrent liability in a schedule of regulatory noncurrent liabilities.

No definition available.

Name:	us-gaap_RegulatoryNoncurrentLiabilityAmortizationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration