Regulatory - Schedule of Regulatory Assets and Regulatory Liabilities (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2012
Regulatory Assets [Line Items]
Amortization period	5
TAMPA ELECTRIC CO [Member]
Regulatory Assets [Line Items]
Amortization period	5

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 71

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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