Segment and Related Information - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,704	$ 1,609	$ 3,275	$ 3,176
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,023	962	1,966	1,915
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	415	402	788	782
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	177	158	346	314
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 89	$ 87	$ 175	$ 165