Software Development and Intellectual Property Licenses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Software development and intellectual property licenses:
Internally-developed software costs	$ 244		$ 291
Payments made to third-party software developers	20		38
Total software development costs	264		$ 329
Amortization:
Amortization of capitalized software development costs and intellectual property licenses	$ 110	$ 152