Stock-Based Compensation (Stock Based Compensation Activity) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Exercise Price, Balance at January 1, 2012	$ 2.89
Granted at fair market value
Weighted Average Exercise Price, Vested/exercised	$ 5.31	[1]
Weighted Average Exercise Price, Canceled	$ 27.40
Weighted Average Exercise Price, Balance at March 31, 2012	$ 2.16	[2],[3]
Number of Options, Balance at January 1, 2012	1,901,000
Number of Options, Vested/exercised	(416,000)	[1]
Number of Options, Canceled	(3,000)
Number of Options, Balance	1,482,000	[2],[3]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	0
Options outstanding, intrinsic value	$ 38
In-the-money' stock options (in number of options)	1,472,000
Stock options exercisable	1,418,000
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Price, Balance	$ 13.64
Weighted Average Grant Price, Granted at fair market value	$ 20.54
Weighted Average Grant Price, Vested/exercised	$ 12.69	[1]
Weighted Average Grant Price, Canceled	$ 14.12
Weighted Average Grant Price, Balance	$ 16.06	[2],[3]
Number of RSUs, Balance	3,497,000
Number of RSUs, Granted at fair market value	1,046,000
Number of RSUs, Vested/exercised	(1,083,000)	[1]
Number of RSUs, Canceled	(47,000)
Number of RSUs, Balance	3,413,000	[2],[3]
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance based stock vested	429,000
Number of performance based stock vested, intrinsic value	8
Options outstanding, intrinsic value	95
Aggregate unrecognized compensation expense related to awards	$ 40
Time-based restricted stock units outstanding	1,338,000
Number of performance-based and market-based stock units outstanding	2,075,000
Restricted Stock Units (RSUs) [Member] | Time-based vesting schedule [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs, Granted at fair market value	585,000
Share-based compensation,RSUs eligible to vest	24,000
Restricted Stock Units (RSUs) [Member] | Performance-Based Vesting Schedule [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs, Granted at fair market value	374,000
Restricted Stock Units (RSUs) [Member] | Market-based vesting schedule [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs, Granted at fair market value	87,000
Share-based compensation,RSUs eligible to vest	9,000

[1] During the three months ended March 31, 2013, 429,000 market-vesting and performance-based restricted stock units vested. Stock options exercised during the three months ended March 31, 2013 had an intrinsic value of $8 million.

[2] As of March 31, 2013, the Company’s outstanding stock options had aggregate intrinsic value of $38 million; there were 1,472,000 “in-the-money” stock options; and aggregate unrecognized compensation expense related to unvested stock options was immaterial. 1,418,000 stock options are exercisable as of March 31, 2013.

[3] As of March 31, 2013, the Company’s outstanding RSUs had an aggregate intrinsic value of $95 million; aggregate unrecognized compensation expense related to RSUs amounted to $40 million; and the balance of RSUs at March 31, 2013, consists of 1,338,000 related to time-based awards and 2,075,000 related to market-vesting and performance-based awards. Approximately 24,000 time-based restricted stock units and 9,000 market-vesting restricted stock units are eligible to vest in 2013, if applicable service criteria are satisfied.