Equity-Method Investments - Summarized Condensed Financial Information of LivingSocial (Detail) (LivingSocial, USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
LivingSocial
Statement of Operations:
Revenue	$ 384		$ 387
Operating expense	494		653
Impairment charge	0		501
Operating loss	(110)		(767)
Net loss	$ (107)	[1]	$ (516)	[1]

[1] The difference between the operating loss and net loss for the nine months ended September 30, 2012 is primarily due to non-operating, non-cash gains on previously held equity positions in companies that LivingSocial acquired during Q1 2012.