Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Goodwill - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Goodwill [Line Items]
Goodwill impairment	$ 4,628	$ 0		$ 4,628	$ 0
North America [Member]
Goodwill [Line Items]
Goodwill impairment				$ 4,628
Reduction in its market capitalization			25.00%
Other [Member]
Goodwill [Line Items]
Percentage difference between fair value and carrying value in respect of goodwill	10.00%		10.00%	10.00%