Software Development and Intellectual Property Licenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Software development and intellectual property licenses:
Internally-developed software costs	$ 291	$ 270
Payments made to third-party software developers	38	183
Total software development costs	329	453
Amortization:
Amortization of capitalized software development costs and intellectual property licenses	$ 501	$ 314	$ 335