Marketable Securities - Contractual maturity (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Marketable securities by contractual maturity
Due in one year or less	$ 501
Due after one year through five years	15
Due after five years through ten years	16
Total marketable securities	$ 532	$ 434

Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

No definition available.

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