Revenues by Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 50,175	$ 37,905	$ 29,321
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	23,502	17,560	14,056
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	4,872	4,057	3,329
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 21,801	$ 16,288	$ 11,936