Segment Information - Schedule of Revenues by Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenues - external									$ 2,996.6	$ 3,209.9	$ 3,363.5
Sales to affiliates									0	0	0
Total revenues	688.4	858.6	752.5	697.1	720.0	877.8	849.5	762.5	2,996.6	3,209.9	3,363.5
Depreciation and amortization									330.6	317.2	305.6
Total interest charges									183.5	197.4	215.5
Internally allocated interest									0	0	0
Provision for income taxes									160.2	153.9	170.0
Net income from continuing operations	45.6	90.2	65.6	44.6	47.3	86.1	72.0	45.4	246.0	250.8	211.6
Discontinued operations attributable to TECO, net of tax									(33.3)	21.8	27.4
Net income attributable to TECO Energy	45.1	44.0	73.1	50.5	53.2	90.2	77.5	51.7	212.7	272.6	239.0
Goodwill	0				55.4				0	55.4	55.4
Total assets	7,356.5				7,322.2				7,356.5	7,322.2	7,278.3
Capital expenditures									505.1	454.1	489.7
Earnings from unconsol. affiliates											0
Restructuring charges											1.5
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Revenues - external									1,980.7	2,019.3	2,161.9
Sales to affiliates									0.6	1.3	1.3
Total revenues									1,981.3	2,020.6	2,163.2
Depreciation and amortization									237.6	222.1	215.9
Total interest charges									109.8	121.8	122.7
Internally allocated interest									0	0	0
Provision for income taxes									120.2	124.8	122.4
Net income from continuing operations									193.1	202.7	208.8
Discontinued operations attributable to TECO, net of tax									0	0	0
Net income attributable to TECO Energy									193.1	202.7	208.8
Goodwill	0				0				0	0	0
Total assets	6,063.9				5,940.9				6,063.9	5,940.9	5,833.3
Capital expenditures									361.7	314.9	331.2
Earnings from unconsol. affiliates											0
Restructuring charges											0
PGS [Member]
Segment Reporting Information [Line Items]
Revenues - external									396.6	450.5	510.7
Sales to affiliates									2.3	3.0	19.2
Total revenues									398.9	453.5	529.9
Depreciation and amortization									50.6	48.4	46.0
Total interest charges									16.0	17.7	18.3
Internally allocated interest									0	0	0
Provision for income taxes									21.5	20.6	21.3
Net income from continuing operations									34.1	32.6	34.1
Discontinued operations attributable to TECO, net of tax									0	0	0
Net income attributable to TECO Energy									34.1	32.6	34.1
Goodwill	0				0				0	0	0
Total assets	1,009.9				932.0				1,009.9	932.0	918.4
Capital expenditures									97.3	71.9	62.4
Earnings from unconsol. affiliates											0
Restructuring charges											0
Other & Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues - external									10.4	7.1	0.9
Sales to affiliates									(2.9)	(4.3)	(20.5)
Total revenues									7.5	2.8	(19.6)
Depreciation and amortization									1.4	1.4	0.2
Total interest charges									50.6	51.0	67.7
Internally allocated interest									(6.8)	(6.7)	(6.6)
Provision for income taxes									(19.6)	(18.1)	(45.9)
Net income from continuing operations									(31.4)	(36.0)	(84.3)
Discontinued operations attributable to TECO, net of tax									(4.0)	(0.6)	(14.2)
Net income attributable to TECO Energy									(35.4)	(36.6)	(98.5)
Goodwill	0				0				0	0	0
Total assets	(238.8)				(240.0)				(238.8)	(240.0)	(98.3)
Capital expenditures									1.2	3.5	47.9
Earnings from unconsol. affiliates											0
Restructuring charges											1.5
TECO Coal [Member]
Segment Reporting Information [Line Items]
Revenues - external									608.9	733.0	690.0
Sales to affiliates									0	0	0
Total revenues									608.9	733.0	690.0
Depreciation and amortization									41.0	45.3	43.5
Total interest charges									7.1	6.9	6.8
Internally allocated interest									6.8	6.7	6.6
Provision for income taxes									15.7	15.4	11.8
Net income from continuing operations									50.2	51.5	53.0
Discontinued operations attributable to TECO, net of tax									0	0	0
Net income attributable to TECO Energy									50.2	51.5	53.0
Goodwill	0				0				0	0	0
Total assets	356.6				385.2				356.6	385.2	332.2
Capital expenditures									36.3	56.6	47.4
Earnings from unconsol. affiliates											0
Restructuring charges											0
TECO Guatemala [Member]
Segment Reporting Information [Line Items]
Revenues - external									0	0	0
Sales to affiliates									0	0	0
Total revenues									0	0	0
Depreciation and amortization									0	0	0
Total interest charges									0	0	0
Internally allocated interest									0	0	0
Provision for income taxes									0	0	0
Net income from continuing operations									0	0	0
Discontinued operations attributable to TECO, net of tax									(29.3)	22.4	41.6
Net income attributable to TECO Energy									(29.3)	22.4	41.6
Goodwill	0				55.4				0	55.4	55.4
Total assets	164.9				304.1				164.9	304.1	292.7
Capital expenditures									8.6	7.2	0.8
Earnings from unconsol. affiliates											0
Restructuring charges											0
TAMPA ELECTRIC CO [Member]
Segment Reporting Information [Line Items]
Revenues - external									2,378.0	2,470.6	2,673.6
Sales to affiliates									0	0	0
Total revenues									2,378.0	2,470.6	2,673.6
Depreciation and amortization									288.2	270.5	261.9
Total interest charges									125.8	139.5	141.0
Provision for income taxes									141.7	145.4	143.7
Net income attributable to TECO Energy									227.2	235.3	242.9
Total assets	6,766.2				6,571.4				6,766.2	6,571.4	6,474.7
Capital expenditures									459.0	386.8	393.6
TAMPA ELECTRIC CO [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Revenues - external									1,980.9	2,020.1	2,162.8
Sales to affiliates									0.4	0.5	0.4
Total revenues									1,981.3	2,020.6	2,163.2
Depreciation and amortization									237.6	222.1	215.9
Total interest charges									109.8	121.8	122.7
Provision for income taxes									120.2	124.8	122.4
Net income attributable to TECO Energy									193.1	202.7	208.8
Total assets	5,782.0				5,693.0				5,782.0	5,693.0	5,614.8
Capital expenditures									361.7	314.9	331.2
TAMPA ELECTRIC CO [Member] | PGS [Member]
Segment Reporting Information [Line Items]
Revenues - external									397.1	450.5	510.8
Sales to affiliates									1.8	3.0	19.1
Total revenues									398.9	453.5	529.9
Depreciation and amortization									50.6	48.4	46.0
Total interest charges									16.0	17.7	18.3
Provision for income taxes									21.5	20.6	21.3
Net income attributable to TECO Energy									34.1	32.6	34.1
Total assets	970.9				888.4				970.9	888.4	876.2
Capital expenditures									97.3	71.9	62.4
TAMPA ELECTRIC CO [Member] | Other & Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues - external									0	0	0
Sales to affiliates									(2.2)	(3.5)	(19.5)
Total revenues									(2.2)	(3.5)	(19.5)
Depreciation and amortization									0	0	0
Total interest charges									0	0	0
Provision for income taxes									0	0	0
Net income attributable to TECO Energy									0	0	0
Total assets	13.3				(10.0)				13.3	(10.0)	(16.3)
Capital expenditures									$ 0	$ 0	$ 0