Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Interest expense	$ 156	$ 144	$ 302	$ 287
Operating Segments
Segment Reporting Information [Line Items]
Interest income	2	1	5	4
Interest expense	$ 10	$ 9	$ 20	$ 21