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Commitments and Contingencies (Legal Proceedings) (Details) $ in Millions, $ in Millions |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Oct. 16, 2020 USD ($) | May 13, 2020 USD ($) | Nov. 30, 2020 USD ($) | Dec. 31, 2020 CAD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2020 USD ($)
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Litigation Settlement, Amount |  |  |  | $ 49 |  | $ 0 |
Prime Rate [Member] | Tampa Electric |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Loss Contingency, Estimate of Possible Loss |  |  |  | $ 22 |  |  | $ 17
Prime Rate [Member] | TGH |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Litigation Settlement, Amount |  |  |  |  | $ 21 |  |
Litigation Settlement Variable Rate |  |  |  | 2.00% | 2.00% |  |
United States Free Trade Agreement Award One [Member] | TGH |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Proceeds from settlement of claims |  |  | $ 38 |  |  |  |
United States Free Trade Agreement Award two [Member] | TGH |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Litigation Settlement, Amount |  | $ 35 |  |  | $ 59 |  |
Litigation Settlement Interest | $ 2 |  |  |  |  |  |

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