Financial Risk Management Activities (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	$ 66	$ 44
Credit Risk Derivative Liabilities, at Fair Value	75	28
Aggregate fair value of derivative contracts in a liability position that contains triggers for additional collateral	29	3
Additional collateral aggregate fair value	46	25
Accumulated Other Comprehensive Income (Loss) on interest rate derivatives	(6)	$ (9)
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ (3)

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Fair value of credit risk derivative liability.

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Fair value, after effects of master netting arrangements, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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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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