Consolidated Statements of Income and Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Franchise fees and gross receipts taxes	$ 111.5	$ 109.3	$ 116.1
TAMPA ELECTRIC CO [Member] \| Electric [Member]
Franchise fees and gross receipts taxes	91.1	85.6	89.8
TAMPA ELECTRIC CO [Member] \| Gas [Member]
Franchise fees and gross receipts taxes	$ 20.4	$ 23.7	$ 26.3

Revenue earned during the period from consideration (often a percentage of the franchisee's sales) received for the right to operate a business using the entity's name, merchandise, services, methodologies, promotional support, marketing, and supplies.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 952

-SubTopic 605

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6490812&loc=d3e68564-108043

Name:	us-gaap_FranchiseRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration