Restructuring Programs - Certain Related Costs Incurred in Connection with Restructuring Programs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Related restructuring costs	$ 0	$ 19	$ 17	$ 96
Retention related severance/bonuses
Restructuring Cost and Reserve [Line Items]
Related restructuring costs	(2)	11	9	31
Contractual severance costs
Restructuring Cost and Reserve [Line Items]
Related restructuring costs	0	3	4	41
Contractual severance costs | HCL Technologies
Restructuring Cost and Reserve [Line Items]
Related restructuring costs				38
Consulting and other costs
Restructuring Cost and Reserve [Line Items]
Related restructuring costs	$ 2	$ 5	$ 4	$ 24