Regulatory - Schedule of Regulatory Assets and Regulatory Liabilities (Parenthetical) (Detail)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
Regulatory Assets [Line Items]
Amortization period	5-year	5-year
Tampa Electric Company [Member]
Regulatory Assets [Line Items]
Amortization period	5-year	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