Income Taxes - Reconciliation of U.S. Statutory Rate to Effective Income Tax Rate on Continuing Basis (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	21.00%
Add (deduct) effect of:
State income taxes, net of federal income tax effect	2.40%	3.80%	2.40%
U.S foreign inclusions and foreign tax credit	3.60%	(1.60%)	2.10%
Foreign rate differential	2.70%	4.90%	0.40%
Change in uncertain tax positions	4.50%	5.90%	0.20%
Change in valuation allowance reserve	3.00%	(5.90%)	0.80%
Impairments	(4.40%)	(3.30%)	(9.70%)
Capital loss	3.00%	25.40%	0.00%
Reversal of outside basis difference	(5.20%)	0.40%	0.00%
Non-deductible compensation	(1.20%)	(1.60%)	(0.10%)
Return to provision	1.70%	2.20%	(0.10%)
Other taxes	(0.90%)	1.60%	0.10%
Outbound transfer of U.S. assets	(6.90%)	68.30%	0.00%
Other	0.20%	0.80%	(0.10%)
Effective rate	23.50%	121.90%	17.00%
Tax benefit related to outbound transfer of domestic assets		$ 522

Effective Income Tax Rate Reconciliation, Capital Loss

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Effective Income Tax Rate Reconciliation, Non-Deductible Compensation Expense, Percent

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Effective income tax rate reconciliation, nondeductible expense, impairment losses, adjustments, percent.

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Effective Income Tax Rate Reconciliation, Other Taxes, Percent

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Effective Income Tax Rate Reconciliation, Outbound Transfer of Domestic Assets

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Effective income tax rate reconciliation reversal of other adjustments.

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Tax Benefit Related to Outbound Transfer of Domestic Assets

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations attributable to deduction. Includes, but is not limited to, dividend deduction, deduction for dividend paid to employee stock ownership plan (ESOP), Medicare prescription drug benefit subsidy deduction, and other deductions.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference, between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, that is attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority interest income (expense), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, change in enacted tax rate, prior year income taxes, change in deferred tax asset valuation allowance, and other adjustments.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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