Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Interest expense	$ 86	$ 90	$ 254	$ 282
Operating Segments
Segment Reporting Information [Line Items]
Interest income	6	4	17	14
Interest expense	$ 8	$ 5	$ 21	$ 15