Taxes - (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Taxes
Provision for/(benefit from) income taxes	$ 373		$ 111	$ (166)	$ (218)
Effective tax rate (as a percent)	13.50%		4.50%	(4.30%)	(5.60%)
Additional provisional charge related to U.S. tax reform	$ (14)	$ 107
Unrecognized tax benefits
Decrease in amount of unrecognized tax benefits				$ 1,013
Unrecognized tax benefits	6,018			6,018
Offsetting tax benefits associated with timing adjustments, U.S. tax credits, potential transfer pricing adjustments, and state income taxes	597			597
Net unrecognized tax benefit amount that, if recognized, would favorably affect the company's effective tax rate	5,421			5,421
India Tax Authorities
Taxes
Prepaid taxes	$ 650			$ 650