Segment Information (Total Revenue By Geographic Region) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Total revenue	$ 2,320	$ 2,225	$ 6,798	$ 6,854
Americas [Member]
Segment Reporting Information [Line Items]
Total revenue	1,578	1,481	4,676	4,602
Europe [Member]
Segment Reporting Information [Line Items]
Total revenue	629	625	1,795	1,869
Asia-Pacific [Member]
Segment Reporting Information [Line Items]
Total revenue	$ 113	$ 119	$ 327	$ 383