Supplemental Information on Unaudited Pro Forma Basis (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Business Acquisition [Line Items]
Revenues	$ 53,656	[1]	$ 47,294	[1]
Net income	$ 10,583		$ 8,792
Net income per share of Class A and Class B common stock-diluted	$ 31.82		$ 26.83

[1] Excludes Home.