Consolidated Statements of Capitalization - Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Long-term debt, total	$ 2,975.4	$ 3,075.8
Unamortized debt disc	(2.7)	(2.4)
Less amount due within one year	0	386.1
Total long-term debt	2,972.7	2,687.3
Long-term debt, carrying amount	2,972.7	3,073.4
TAMPA ELECTRIC CO [Member]
Long-term debt, total	1,702.5
Less amount due within one year	0	374.9
Total long-term debt	1,932.6	1,616.3
TAMPA ELECTRIC CO [Member] \| Carrying Amount [Member]
Long-term debt, carrying amount		1,991.2
Long-term debt, fair value		2,296.5
PGS [Member]
Long-term debt, total	231.7	223.4
PGS [Member] \| 6.875% Notes [Member]
Due	2012
Long-term debt, total	0	19.0
PGS [Member] \| 6.375% Notes [Member]
Due	2012
Long-term debt, total	0	44.3
PGS [Member] \| 6.1% Notes [Member]
Due	2018
Long-term debt, total	50.0	50.0
PGS [Member] \| 5.4% Notes [Member]
Due	2021
Long-term debt, total	46.7	46.7
PGS [Member] \| 2.6% Notes [Member]
Due	2022
Long-term debt, total	25.0	0
PGS [Member] \| 6.15% Notes [Member]
Due	2037
Long-term debt, total	60.0	60.0
PGS [Member] \| 4.1% Notes [Member]
Due	2042
Long-term debt, total	50.0	0
PGS [Member] \| 8.00% Senior Notes [Member]
Due	2012
Long-term debt, total	0	3.4
Long-Term Debt [Member]
Long-term debt, total	1,932.6	1,991.2
Long-term debt, carrying amount	1,934.2	1,992.3
Long-term debt, fair value	2,270.3
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member]
Long-term debt, total	1,702.5	1,768.9
Unamortized debt disc	(1.6)	(1.1)
Less amount due within one year	0	374.9
Total long-term debt	1,932.6	1,616.3
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 1.5% term rate bonds repurchased in 2011 [Member]
Due	2030
Long-term debt, total	0	0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.1% Refunding bonds [Member]
Due	2013
Long-term debt, total	0	60.7
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.65% Refunding bonds [Member]
Due	2018
Long-term debt, total	54.2	54.2
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| Variable rate bonds repurchased in 2008 Due To 2020 [Member]
Due	2020
Long-term debt, total	0	0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.5% Refunding bonds [Member]
Due	2023
Long-term debt, total	0	86.4
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.15% Refunding bonds [Member]
Due	2025
Long-term debt, total	51.6	51.6
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.0% Refunding bonds [Member]
Due	2034
Long-term debt, total	0	86.0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.875% Notes [Member]
Due	2012
Long-term debt, total	0	99.6
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.375% Notes [Member]
Due	2012
Long-term debt, total	0	208.7
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.25% Notes [Member]
Maturity range start	2014
Maturity range end	2016
Long-term debt, total	250.0	250.0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.1% Notes [Member]
Due	2018
Long-term debt, total	200.0	200.0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 5.4% Notes [Member]
Due	2021
Long-term debt, total	231.7	231.7
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 2.6% Notes [Member]
Due	2022
Long-term debt, total	225.0	0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.55% Notes [Member]
Due	2036
Long-term debt, total	250.0	250.0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 6.15% Notes [Member]
Due	2037
Long-term debt, total	190.0	190.0
Long-Term Debt [Member] \| TAMPA ELECTRIC CO [Member] \| 4.1% Notes [Member]
Due	2042
Long-term debt, total	250.0	0
Long-Term Debt [Member] \| PGS [Member]
Long-term debt, total	231.7	223.4
Long-Term Debt [Member] \| PGS [Member] \| 6.875% Notes [Member]
Due	2012
Long-term debt, total	0	19.0
Long-Term Debt [Member] \| PGS [Member] \| 6.375% Notes [Member]
Due	2012
Long-term debt, total	0	44.3
Long-Term Debt [Member] \| PGS [Member] \| 6.1% Notes [Member]
Due	2018
Long-term debt, total	50.0	50.0
Long-Term Debt [Member] \| PGS [Member] \| 5.4% Notes [Member]
Due	2021
Long-term debt, total	46.7	46.7
Long-Term Debt [Member] \| PGS [Member] \| 2.6% Notes [Member]
Due	2022
Long-term debt, total	25.0	0
Long-Term Debt [Member] \| PGS [Member] \| 6.15% Notes [Member]
Due	2037
Long-term debt, total	60.0	60.0
Long-Term Debt [Member] \| PGS [Member] \| 4.1% Notes [Member]
Due	2042
Long-term debt, total	50.0	0
Long-Term Debt [Member] \| PGS [Member] \| 8.00% Senior Notes [Member]
Due	2012
Long-term debt, total	$ 0	$ 3.4

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References+ Details

The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28567-108399

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 20

-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.

+ Details

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References+ Details