Marketable and Other Securities - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Marketable Securities [Abstract]
Cash and cash equivalents	$ 26,939	$ 19,069
Restricted cash included in Other current assets	2,419
Restricted cash included in Other assets	498
Total	$ 29,856	$ 22,943	$ 22,899	$ 23,496

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant