Effective income tax rate reconciliation assets expensing.

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- Definition

Income taxes.

+ References

No definition available.

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- Definition

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

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- Definition

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

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- Definition

Amount of unrecognized tax benefits.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Income Taxes [Line Items]
Federal statutory tax rate	21.00%		35.00%
Asset expensing	100.00%
Unrecognized tax benefits	$ 8			$ 8
Unrecognized tax benefit that would reduce effective tax rate	$ 8			$ 8
Tampa Electric [Member]
Income Taxes [Line Items]
Effective tax rate	20.00%	18.20%