Segment Information - Schedule of Segment Reporting Information, by Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Interest expense included in the segment results	$ 98	$ 78	$ 197	$ 158
Interest Income Excluded From Segment Information [Member]
Segment Reporting Information [Line Items]
Interest income included in the segment results	2		2
Interest Expense Excluded From Segment Information [Member]
Segment Reporting Information [Line Items]
Interest expense included in the segment results	$ 6	$ 2	$ 12	$ 2