Income Taxes [Line Items]

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- Definition

Increase in regulatory liabilities of regulated utility subsidiaries related to remeasurement of deferred tax liability from change in tax rate pursuant to Tax Cuts and Jobs Act.

+ References

No definition available.

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- Definition

Reduction in income tax liability from the remeasurement of deferred tax liability from change in tax rate pursuant to Tax Cuts and Jobs Act.

+ References

No definition available.

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- Definition

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

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- Definition

Tax year being audited in the income tax examination, in CCYY format.

+ References

No definition available.

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- Definition

Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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- Definition

Amount of income tax expense (benefit) for remeasurement of deferred tax from change in tax rate pursuant to Tax Cuts and Jobs Act.

+ References

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- Definition

Amount of reasonable estimate for income tax expense (benefit) for which accounting for tax effect is incomplete pursuant to Tax Cuts and Jobs Act.

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- Definition

Amount of reasonable estimate for income tax expense for which accounting for tax effect from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated is incomplete pursuant to Tax Cuts and Jobs Act.

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- Definition

Amount of unrecognized tax benefits.

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- Definition

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

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Income taxes - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
Income taxes - Narrative (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2018
Income Taxes [Line Items]
Statutory U.S. Corporate income tax rate	21.00%	35.00%
Reduction in deferred income tax liabilities related to reduction in U.S. statutory income tax rate		$ 35,600
Income tax benefit related to reduction in U.S. statutory income tax rate		29,600
Increase in regulatory liabilities for deferred income tax liability reduction related to reduction in U.S. statutory income tax rate		6,000
Income tax charge with respect to deemed repatriation of accumulated undistributed earnings of foreign subsidiaries		1,400
Net income tax benefit as a result of enactment of the TCJA		$ 28,200
Unrecognized tax benefits	$ 952		$ 549
Unrecognized tax benefits that would impact effective tax rate	795
Tax Equity Investment Funds [Member]
Income Taxes [Line Items]
Income tax expense for uncertain tax positions	$ 377
Tax Year 2012 [Member]
Income Taxes [Line Items]
Income tax examination, year under examination	2012
Tax Year 2016 [Member]
Income Taxes [Line Items]
Income tax examination, year under examination	2016