Cash and Cash Equivalents - Securities Purchased Under Agreements (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Average securities purchased under agreements to resell	$ 286	$ 149
Maximum amount outstanding at any month-end during the year	$ 762	$ 450

Average amount outstanding of securities purchased under agreements to resell.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (a)

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (b)
-Subparagraph (1)

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