Business Segments - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3
Cash and cash equivalents	$ 801	$ 1,043	$ 1,132
Europe, Middle East and Africa
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 261	$ 355
Concentrations of cash and cash equivalents	33.00%	34.00%
Asia Pacific
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 278	$ 344
Concentrations of cash and cash equivalents	35.00%	33.00%
Americas
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 134	$ 169
Concentrations of cash and cash equivalents	17.00%	16.00%