Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 07, 2021	Apr. 20, 2021	Oct. 27, 2020	Sep. 30, 2021	Dec. 31, 2020	Mar. 31, 2019
Other Commitments [Line Items]
Accrued Liabilities and Other Liabilities				$ 2,418	$ 2,519
Syntel Sterling Best Shores Mauritius Ltd. [Member]
Other Commitments [Line Items]
Litigation settlement, amount awarded from other party		$ 570	$ 855
Litigation Settlement Amount Awarded From Other Party, Punitive Damages		285	$ 570
Litigation Settlement Amount Awarded From Other Party, Actual Damages		$ 285
Consolidated Putative Securities Class Action
Other Commitments [Line Items]
Litigation Settlement, Amount Awarded to Other Party	$ 95
Executive Insurance Policy, Insurance Reserve	75
Gain (Loss) Related to Litigation Settlement	$ 20
India Defined Contribution Obligation [Member]
Other Commitments [Line Items]
Accrued Liabilities and Other Liabilities						$ 117