Segment Information (Schedule Of Revenues By Segment) (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenues - external	$ 911.4		$ 901.8		$ 2,593.2		$ 2,712.9
Sales to affiliates	0		0		0		0
Total revenues	911.4		901.8		2,593.2		2,712.9
Equity earnings of unconsolidated affiliates	0		3.6		0		10.5
Depreciation	82.4		78.8		243.4		233.7
Restructuring charges					0		1.5
Total interest charges	50.7	[1]	57.4	[1]	154.5	[1]	174.9	[1]
Internally allocated interest	0	[1]	0	[1]	0	[1]	0	[1]
Provision (benefit) for taxes	51.2		65.5		123.7		135.9
Net income (loss)	90.2		51.0		219.4		182.3
Goodwill	55.4				55.4				55.4
Total assets	7,295.9				7,295.9				7,194.6
Tampa Electric Co [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Revenues - external	591.8		593.3		1,571.2		1,670.9
Sales to affiliates	0.1		0.3		0.4		1.0
Total revenues	591.9		593.6		1,571.6		1,671.9
Depreciation	56.2		54.4		166.4		161.0
Total interest charges	30.3		30.7		91.6		91.8
Provision (benefit) for taxes	47.4		36.8		104.3		98.4
Net income (loss)	75.0		61.9		165.0		166.8
Total assets	5,691.7				5,691.7				5,580.6
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Revenues - external	591.6		593.3		1,570.6		1,670.9
Sales to affiliates	0.3		0.3		1.0		1.0
Total revenues	591.9		593.6		1,571.6		1,671.9
Equity earnings of unconsolidated affiliates			0				0
Depreciation	56.2		54.4		166.4		161.0
Restructuring charges							0
Total interest charges	30.3	[1]	30.7	[1]	91.6	[1]	91.8	[1]
Internally allocated interest	0	[1]	0	[1]	0	[1]	0	[1]
Provision (benefit) for taxes	47.4		36.8		104.3		98.4
Net income (loss)	75.0		61.9		165.0		166.8
Goodwill	0				0				0
Total assets	5,924.3				5,924.3				5,833.3
Tampa Electric Co [Member] | Peoples Gas [Member]
Segment Reporting Information [Line Items]
Revenues - external	93.8		114.1		358.5		408.2
Sales to affiliates	0.4		2.5		3.0		17.4
Total revenues	94.2		116.6		361.5		425.6
Depreciation	12.2		11.5		36.0		34.3
Total interest charges	4.4		4.6		13.3		13.8
Provision (benefit) for taxes	3.0		2.4		16.0		16.9
Net income (loss)	4.8		3.7		25.4		26.7
Total assets	840.4				840.4				872.7
Peoples Gas [Member]
Segment Reporting Information [Line Items]
Revenues - external	93.9		114.1		358.5		408.2
Sales to affiliates	0.3		2.5		3.0		17.4
Total revenues	94.2		116.6		361.5		425.6
Equity earnings of unconsolidated affiliates			0				0
Depreciation	12.2		11.5		36.0		34.3
Restructuring charges							0
Total interest charges	4.4	[1]	4.6	[1]	13.3	[1]	13.8	[1]
Internally allocated interest	0	[1]	0	[1]	0	[1]	0	[1]
Provision (benefit) for taxes	3.0		2.4		16.0		16.9
Net income (loss)	4.8		3.7		25.4		26.7
Goodwill	0				0				0
Total assets	879.2				879.2				918.4
Teco Coal [Member]
Segment Reporting Information [Line Items]
Revenues - external	190.5		165.3		555.5		537.9
Sales to affiliates	0		0		0		0
Total revenues	190.5		165.3		555.5		537.9
Equity earnings of unconsolidated affiliates			0				0
Depreciation	11.8		11.0		34.4		32.8
Restructuring charges							0
Total interest charges	1.7	[1]	1.6	[1]	5.1	[1]	5.2	[1]
Internally allocated interest	1.7	[1]	1.5	[1]	5.0	[1]	5.0	[1]
Provision (benefit) for taxes	4.1		2.2		10.7		9.1
Net income (loss)	14.1		8.3		38.1		45.8
Goodwill	0				0				0
Total assets	352.5				352.5				332.2
Teco Guatemala [Member]
Segment Reporting Information [Line Items]
Revenues - external	33.6		29.0		103.3		95.7
Sales to affiliates	0		0		0		0
Total revenues	33.6		29.0		103.3		95.7
Equity earnings of unconsolidated affiliates			4.1				12.1
Depreciation	1.8		1.8		5.5		5.4
Restructuring charges							0
Total interest charges	1.9	[1]	4.0	[1]	5.7	[1]	13.0	[1]
Internally allocated interest	1.5	[1]	3.0	[1]	4.6	[1]	9.5	[1]
Provision (benefit) for taxes	2.4		29.1		8.5		35.9
Net income (loss)	4.5		(12.6)		16.4		8.4
Goodwill	55.4				55.4				55.4
Total assets	266.4				266.4				292.7
Tampa Electric Co [Member] | Other & Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues - external	0		0		0		0
Sales to affiliates	(0.5)		(2.6)		(3.4)		(17.7)
Total revenues	(0.5)		(2.6)		(3.4)		(17.7)
Depreciation	0		0		0		0
Total interest charges	0		0		0		0
Provision (benefit) for taxes	0		0		0		0
Net income (loss)	0		0		0		0
Total assets	(5.9)				(5.9)				(14.8)
Other & Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues - external	1.8		0.1		5.3		0.2
Sales to affiliates	(0.6)		(2.8)		(4.0)		(18.4)
Total revenues	1.2		(2.7)		1.3		(18.2)
Equity earnings of unconsolidated affiliates			(0.5)				(1.6)
Depreciation	0.4		0.1		1.1		0.2
Restructuring charges							1.5
Total interest charges	12.4	[1]	16.5	[1]	38.8	[1]	51.1	[1]
Internally allocated interest	(3.2)	[1]	(4.5)	[1]	(9.6)	[1]	(14.5)	[1]
Provision (benefit) for taxes	(5.7)		(5.0)		(15.8)		(24.4)
Net income (loss)	(8.2)		(10.3)		(25.5)		(65.4)
Goodwill	0				0				0
Total assets	(126.5)				(126.5)				(182.0)
Tampa Electric Co [Member]
Segment Reporting Information [Line Items]
Revenues - external	685.6		707.4		1,929.7		2,079.1
Sales to affiliates	0		0.2		0		0.7
Total revenues	685.6		707.6		1,929.7		2,079.8
Depreciation	68.4		65.9		202.4		195.3
Total interest charges	34.7		35.3		104.9		105.6
Provision (benefit) for taxes	50.4		39.2		120.3		115.3
Net income (loss)	79.8		65.6		190.4		193.5
Total assets	$ 6,526.2				$ 6,526.2				$ 6,438.5

[1] Segment net income is reported on a basis that includes internally allocated financing costs. Total interest charges include internally allocated interest costs that for January 2011 through September 2011 were at a pretax rate of 6.25%, for July 2010 through December 2010 were at a pretax rate of 6.50%, and for January 2010 through June 2010 were at a pretax rate of 7.15% based on an average of each subsidiary's equity and indebtedness to TECO Energy assuming a 50/50 debt/equity capital structure.