Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Interest expense	$ 86	$ 90	$ 169	$ 193
Operating Segments
Segment Reporting Information [Line Items]
Interest income	6	5	11	10
Interest expense	$ 7	$ 4	$ 13	$ 10