Income and Other Taxes - Unrecognized Tax Benefits Rollforward (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, Beginning		$ 165	$ 222	$ 207
Additions (Reductions) related to current year		1	(9)	36
Additions related to prior years positions		10	0	0
Reductions related to prior years positions		(46)	(31)	(5)
Settlements with taxing authorities	[1]	(5)	0	(6)
Reductions related to lapse of statute of limitations		(3)	(2)	(9)
Currency		3	(2)	(1)
Tax Positions assumed in Conduent Separation		0	(13)	0
Balance, Ending		125	165	222
Unrecognized Tax Benefits, Reasonably Possible but Uncertainty of Timing		8	5	9
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		$ 5	$ 10	$ 2

[1] Majority of settlements did not result in the utilization of cash.