Revenue by Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 1,184		$ 895		$ 2,242		$ 1,626
UNITED STATES
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	588		515		1,124		942
Rest of World
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 596	[1]	$ 380	[1]	$ 1,118	[1]	$ 684	[1]

[1] No individual country exceeded 10% of our total revenue for any period presented