Changes in Composition of Accumulated Other Comprehensive Income or Loss (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (316)	$ (190)	$ (56)
Other comprehensive income (loss)	76	(123)	(137)
Other comprehensive income (loss)	1	(3)	3
Other comprehensive income (loss)	77	(126)	(134)
Ending Balance	(239)	(316)	(190)
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	10	13	10
Other comprehensive income (loss)	1	(3)	3
Ending Balance	11	10	13
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(326)	(203)	(66)
Other comprehensive income (loss)	76	(123)	(137)
Ending Balance	$ (250)	$ (326)	$ (203)