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Regulatory Assets and Liabilities (ROE of Tampa Electric) (Details) - Tampa Electric Division [Member] - Florida Public Service Commission [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 110
Public Utilities Approved Return On Equity Percentage Trigger Rate Minimum	9.25%
Public Utilities Approved Return On Equity Percentage Trigger Rate Minimum Bond Rate Threshold	9.50%
Public Utilities Approved Return On Equity Percentage Trigger Rate Maximum	11.25%
Public Utilities Approved Return On Equity Percentage Trigger Rate Maximum Bond Rate Threshold	11.50%
Public Utilities, Approved Equity Capital Structure, Percentage	54.00%
Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage	9.25%
Public Utilities Approved Rate Increase (Decrease) Percentage Bond Rate Threshold	10.25%
Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage	11.25%
Public Utilities Approved Rate Increase (Decrease) Percentage Bond Rate Threshold	10.50%

X

- Definition

Percentage of public utility's approved return on equity contingent on bond rates exceeding threshold

+ References

No definition available.

+ Details

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- Definition

Maximum trigger rate percentage of public utility's approved return on equity to allow any party to agreement to request review of rates

+ References

No definition available.

+ Details

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- Definition

Maximum trigger rate percentage of public utility's approved return on equity to allow any party to agreement to request review of rates contingent on bond rates exceeding threshold.

+ References

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+ Details

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- Definition

Minumum trigger rate percentage of public utility's approved return on equity to allow utility to request early rate increase

+ References

No definition available.

+ Details

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- Definition

Minumum trigger rate percentage of public utility's approved return on equity to allow utility to request early rate increase contingent on bond rates exceeding threshold.

+ References

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+ Details

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- Definition

Percentage of public utility's approved equity to capital, including debt and equity.

+ References

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- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

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- Definition

Percentage of public utility's approved return on equity.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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