Comprehensive Income and Capital Structure Accumulated Other Comprehensive Income Activity (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at year-end 2012	$ (44)
Other comprehensive income (loss) before reclassifications	(3)
Amounts reclassified from accumulated other comprehensive loss	(7)
Net other comprehensive income (loss)	(10)
Balance at June 30, 2013	(54)
Other comprehensive income (loss), before reclassifications, other derivative instrument adjustments, deferred tax	1
Other comprehensive income (loss), before reclassifications, unrealized gains on available-for-sale securities, deferred tax	2
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at year-end 2012	(32)
Other comprehensive income (loss) before reclassifications	(13)
Amounts reclassified from accumulated other comprehensive loss	0
Net other comprehensive income (loss)	(13)
Balance at June 30, 2013	(45)
Other Derivative Instrument Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at year-end 2012	(19)
Other comprehensive income (loss) before reclassifications	6	[1]
Amounts reclassified from accumulated other comprehensive loss	(1)
Net other comprehensive income (loss)	5
Balance at June 30, 2013	(14)
Unrealized Gains on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at year-end 2012	7
Other comprehensive income (loss) before reclassifications	4	[1]
Amounts reclassified from accumulated other comprehensive loss	(6)
Net other comprehensive income (loss)	(2)
Balance at June 30, 2013	$ 5

[1] We present the portions of other comprehensive income (loss) before reclassifications for the 2013 first half that relate to other derivative instrument adjustments net of $1 million of deferred taxes and the portions that relate to unrealized gains on available-for-sale securities net of $2 million of deferred taxes.