Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Interest expense	$ 142	$ 149	$ 281	$ 282
Operating Segments
Segment Reporting Information [Line Items]
Interest income	6	6	11	12
Interest expense	$ 14	$ 13	$ 27	$ 26