Software Development and Intellectual Property Licenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Software development and intellectual property licenses:
Internally-developed software costs	$ 325		$ 325		$ 291
Payments made to third-party software developers	24		24		38
Total software development costs	349		349		$ 329
Amortization:
Amortization of capitalized software development costs and intellectual property licenses	$ 11	$ 33	$ 175	$ 242