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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Interest expense included in the segment results	$ 98	$ 89	$ 294	$ 246
Interest Income Excluded From Segment Information
Segment Reporting Information [Line Items]
Interest income included in the segment results	3		5
Interest Expense Excluded From Segment Information
Segment Reporting Information [Line Items]
Interest expense included in the segment results	$ 6	$ 3	$ 17	$ 5