Income Taxes (Details) $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Valuation Allowance Rollforward [Roll Forward]
Balance at beginning of year	$ 2,817
Additions to valuation allowance charged to income tax expense	264
Reductions to valuation allowance credited to income tax benefit	(73)
Foreign currency translation	(4)
Balance at end of period	$ 3,004

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant