Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Interest expense	$ 90	$ 98	$ 282	$ 294
Interest Income Excluded From Segment Information
Segment Reporting Information [Line Items]
Interest income included in the segment results	5	3	15	6
Interest Expense Excluded From Segment Information
Segment Reporting Information [Line Items]
Interest expense	$ 6	$ 6	$ 15	$ 17