Decrease of deferred tax assets valuation allowance,

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Deferred tax assets federal capital loss carry forwards expiration date.

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No definition available.

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Deferred tax assets operating loss carry forwards expiration date.

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No definition available.

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- Definition

Deferred tax assets tax credit carry forwards general business expiration date.

+ References

No definition available.

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- Definition

Income tax examination statute of limitations period.

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No definition available.

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- Definition

Income taxes.

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No definition available.

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- Definition

Percentage greater than threshold of income tax examination minimum likelihood of tax benefits being realized upon settlement.

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No definition available.

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- Definition

Statutes of limitations period.

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No definition available.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible capital loss carryforwards.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates.

+ References

No definition available.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible general business tax credit carryforwards.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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- Definition

The amount of estimated interest accrued as of the balance sheet date arising from income tax examinations.

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The amount of estimated penalties recognized in the period arising from income tax examinations.

+ References

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of interest expense for an underpayment of income taxes.

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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Income tax expense from continuing operations	$ 155,300,000	$ 138,900,000	$ 112,600,000
Cash paid for income taxes	$ 14,500,000	$ 2,900,000	$ 1,800,000
Effective tax rate	35.00%	35.00%	35.00%
Deferred tax assets expiration date	2025 and 2034, with the majority expiring in 2025
General business credit	$ 5,800,000
Deferred tax general business credits expiration date	2026 and 2034
Tax credit carry forwards	$ 213,500,000	$ 214,000,000
Valuation allowance	2,000,000	4,600,000
Decrease of valuation allowance	$ 2,600,000
Tax benefits, likelihood of being realized upon ultimate settlement	50.00%
Pretax charges (benefits)	$ 0	0	$ (900,000)
Interest accrued	0	0
Penalties	$ 0
Income tax examination period	1 year
Minimum [Member]
Income Taxes [Line Items]
Statutes of limitations	3 years
Maximum [Member]
Income Taxes [Line Items]
Statutes of limitations	4 years
Federal [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	$ 1,728,600,000
Florida [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	675,200,000
New Mexico [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	85,800,000
NMGI [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	121,600,000
TECO Coal [Member] \| Discontinued Operations [Member]
Income Taxes [Line Items]
Valuation allowance	$ 1,000,000	3,600,000
Deferred tax assets expiration date	2020
TECO Coal [Member] \| Federal [Member] \| Discontinued Operations [Member]
Income Taxes [Line Items]
Capital loss carryforward deferred tax asset	$ 1,000,000
Tampa Electric Company [Member]
Income Taxes [Line Items]
Income tax expense from continuing operations	165,500,000	155,900,000	138,800,000
Cash paid for income taxes	$ 63,700,000	$ 52,600,000	$ 56,400,000
Effective tax rate	35.00%	35.00%	35.00%
Deferred tax assets expiration date	2033
General business credit	$ 1,900,000
Deferred tax general business credits expiration date	2028 and 2035
Tax benefits, likelihood of being realized upon ultimate settlement	50.00%
Statutes of limitations	3 years
Income tax examination period	1 year
Tampa Electric Company [Member] \| Federal [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	$ 194,100,000
Tampa Electric Company [Member] \| Florida [Member]
Income Taxes [Line Items]
Federal, Florida and New Mexico net operating losses (NOL's) carry forward	$ 268,500,000