Related Party Transactions - Schedule of Related Parties (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Natural gas sales to/(from) affiliates	$ (236)	$ (139)	$ (111)
Services received from affiliates	7	6	65
Dividends to TECO Energy	450	408	373
Equity contributions from TECO Energy	580	505	395
Affiliate [Member]
Related Party Transaction [Line Items]
Accounts receivable excluding asset management agreements	4	7
Accounts payable	35	27
Taxes payable	9	19
Emera Energy Services Inc [Member]
Related Party Transaction [Line Items]
Accounts receivable related to asset management agreements to Emera Energy Services Inc.	4	4
TECO Energy [Member]
Related Party Transaction [Line Items]
Dividends to TECO Energy	450	408	373
Equity contributions from TECO Energy	$ 580	$ 505	$ 395

Accounts receivable excluding asset management agreements.

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Accounts receivable related to asset management agreements.

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Natural gas sales to (from) affiliates.

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Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.

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Amount of transactions with related party during the financial reporting period.

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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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Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes.

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