Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	$ 0	$ 7	$ 0	$ 17
Other exit costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	0	4	0	8
inventory related charges [Member] | Cost of Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	0	0	0	4
Asset related charges [Member] | Software and Software Development Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	0	0	0	2
Discrete charge under ASC 712 [Member] | Severance and other employee related charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	0	2	0	4
Severance charge under ASC 420 [Member] | Severance and other employee related charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other asset-related charges	$ 0	$ 1	$ 0	$ (1)