Segment Information - Schedule of Segment Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Total revenues	$ 687.2	$ 642.1	$ 1,870.9	$ 1,792.9
Depreciation and amortization	78.6	76.1	230.0	222.8
Total interest charges	42.9	39.9	123.2	121.6
Provision for income taxes	33.7	38.9	98.0	91.4
Net income from continuing operations	73.0	64.3	179.0	153.3
Income from discontinued operations, net	(61.9)	(1.5)	(59.4)	2.4
Net income	11.1	62.8	119.6	155.7
Income (Loss) from discontinued operations, net	(61.9)	(1.5)	(59.4)	2.4
Goodwill	401.8		401.8		0	0
Assets held for sale, current	133.7		133.7			0
Assets held for sale, non-current	78.6		78.6			0
Total assets	8,653.6		8,653.6			7,448.0
Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Total revenues	668.5	639.4	1,847.3	1,783.3
Depreciation and amortization	75.4	75.6	225.9	221.6
Total interest charges	27.3	26.2	79.4	79.6
Provision for income taxes	51.5	46.1	129.2	111.1
Net income	84.5	74.1	214.0	178.2
Total assets	7,154.3	6,875.8	7,154.3	6,875.8		6,875.8
Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	581.8	556.4	1,547.7	1,477.3
Depreciation and amortization	61.8	62.2	185.6	182.0
Total interest charges	23.8	22.8	69.1	69.5
Provision for income taxes	48.5	42.7	112.2	94.0
Net income	79.7	68.7	187.1	151.1
Total assets	6,160.8	5,895.4	6,160.8	5,895.4
People Gas [Member]
Segment Reporting Information [Line Items]
Total revenues	86.9	83.4	300.6	307.1
Depreciation and amortization	13.6	13.4	40.3	39.6
Total interest charges	3.5	3.4	10.3	10.1
Provision for income taxes	3.0	3.4	17.0	17.1
Net income	4.8	5.4	26.9	27.1
Total assets	1,002.4	989.3	1,002.4	989.3
New Mexico Gas Company [Member]
Segment Reporting Information [Line Items]
Total revenues	16.2	0	16.2	0
Depreciation and amortization	2.8	0	2.8	0
Total interest charges	1.1	0	1.1	0
Provision for income taxes	(0.5)	0	(0.5)	0
Net income from continuing operations	(0.9)	0	(0.9)	0
Income from discontinued operations, net	0	0	0	0
Net income	(0.9)	0	(0.9)	0
Income (Loss) from discontinued operations, net	0	0	0	0
Goodwill	401.8		401.8
Assets held for sale, current	0		0
Assets held for sale, non-current	0		0
Total assets	1,171.4		1,171.4			0
TECO Coal [Member]
Segment Reporting Information [Line Items]
Total revenues			0	0
Depreciation and amortization			0	0
Total interest charges			0	0
Provision for income taxes			0	0
Net income from continuing operations			0	0
Income from discontinued operations, net			(65.6)	2.3
Net income			(65.6)	2.3
Income (Loss) from discontinued operations, net			(65.6)	2.3
Goodwill	0		0
Assets held for sale, current	133.7		133.7
Assets held for sale, non-current	78.6		78.6
Total assets	261.8		261.8			316.3
Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	687.2	642.1	1,870.9	1,792.9
Revenues - External [Member] | Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Total revenues	668.5	639.4	1,847.3	1,783.3
Revenues - External [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	581.6	556.3	1,547.3	1,477.0
Revenues - External [Member] | People Gas [Member]
Segment Reporting Information [Line Items]
Total revenues	86.9	83.1	300.0	306.3
Revenues - External [Member] | New Mexico Gas Company [Member]
Segment Reporting Information [Line Items]
Total revenues	16.2	0	16.2	0
Revenues - External [Member] | TECO Coal [Member]
Segment Reporting Information [Line Items]
Total revenues			0	0
Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0	0	0
Sales to Affiliates [Member] | Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0	0	0
Sales to Affiliates [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0.2	0.1	0.4	0.3
Sales to Affiliates [Member] | People Gas [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0.3	0.6	0.8
Sales to Affiliates [Member] | New Mexico Gas Company [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0	0	0
Sales to Affiliates [Member] | TECO Coal [Member]
Segment Reporting Information [Line Items]
Sales to affiliates			0	0
Operating Segments [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	581.8	556.4	1,547.7	1,477.3
Depreciation and amortization	61.8	62.2	185.6	182.0
Total interest charges	23.8	22.8	69.1	69.5
Provision for income taxes	48.5	42.7	112.2	94.0
Net income from continuing operations	79.7	68.7	187.1	151.1
Income from discontinued operations, net	0	0	0	0
Net income	79.7	68.7	187.1	151.1
Income (Loss) from discontinued operations, net	0	0	0	0
Goodwill	0		0
Assets held for sale, current	0		0
Assets held for sale, non-current	0		0
Total assets	6,485.5		6,485.5			6,126.9
Operating Segments [Member] | People Gas [Member]
Segment Reporting Information [Line Items]
Total revenues	86.9	83.4	300.6	307.1
Depreciation and amortization	13.6	13.4	40.3	39.6
Total interest charges	3.5	3.4	10.3	10.1
Provision for income taxes	3.0	3.4	17.0	17.1
Net income from continuing operations	4.8	5.4	26.9	27.1
Income from discontinued operations, net	0	0	0	0
Net income	4.8	5.4	26.9	27.1
Income (Loss) from discontinued operations, net	0	0	0	0
Goodwill	0		0
Assets held for sale, current	0		0
Assets held for sale, non-current	0		0
Total assets	1,034.1		1,034.1			1,021.2
Operating Segments [Member] | TECO Coal [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0
Depreciation and amortization	0	0
Total interest charges	0	0
Provision for income taxes	0	0
Net income from continuing operations	0	0
Income from discontinued operations, net	(64.8)	(1.4)
Net income	(64.8)	(1.4)
Income (Loss) from discontinued operations, net	(64.8)	(1.4)
Operating Segments [Member] | Revenues - External [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Total revenues	581.5	556.2	1,546.9	1,476.6
Operating Segments [Member] | Revenues - External [Member] | People Gas [Member]
Segment Reporting Information [Line Items]
Total revenues	86.9	83.1	300.0	306.3
Operating Segments [Member] | Revenues - External [Member] | TECO Coal [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0
Operating Segments [Member] | Sales to Affiliates [Member] | Tampa Electric [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0.3	0.2	0.8	0.7
Operating Segments [Member] | Sales to Affiliates [Member] | People Gas [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0.3	0.6	0.8
Operating Segments [Member] | Sales to Affiliates [Member] | TECO Coal [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	0	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total revenues	2.3	2.3	6.4	8.5
Depreciation and amortization	0.4	0.5	1.3	1.2
Total interest charges	14.5	13.7	42.7	42.0
Provision for income taxes	(17.3)	(7.2)	(30.7)	(19.7)
Net income from continuing operations	(10.6)	(9.8)	(34.1)	(24.9)
Income from discontinued operations, net	2.9	(0.1)	6.2	0.1
Net income	(7.7)	(9.9)	(27.9)	(24.8)
Income (Loss) from discontinued operations, net	2.9	(0.1)	6.2	0.1
Goodwill	0		0
Assets held for sale, current	0		0
Assets held for sale, non-current	0		0
Total assets	(299.2)		(299.2)			(16.4)
Intersegment Eliminations | Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Total revenues	(0.2)	(0.4)	(1.0)	(1.1)
Depreciation and amortization	0	0	0	0
Total interest charges	0	0	0	0
Provision for income taxes	0	0	0	0
Net income	0	0	0	0
Total assets	(8.9)	(8.9)	(8.9)	(8.9)
Intersegment Eliminations | Revenues - External [Member]
Segment Reporting Information [Line Items]
Total revenues	2.6	2.8	7.8	10.0
Intersegment Eliminations | Revenues - External [Member] | Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Intersegment Eliminations | Sales to Affiliates [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	(0.3)	(0.5)	(1.4)	(1.5)
Intersegment Eliminations | Sales to Affiliates [Member] | Tampa Electric Company [Member]
Segment Reporting Information [Line Items]
Sales to affiliates	$ (0.2)	$ (0.4)	$ (1.0)	$ (1.1)