Segment and Related Information - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,689	$ 1,546	$ 4,964	$ 4,721
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,013	934	2,974	2,850
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	419	378	1,212	1,159
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	174	160	522	473
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 83	$ 74	$ 256	$ 239