Stock-Based Compensation (Stock Based Compensation Activity) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Dec. 31, 2011
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	$ 0
Weighted Average Exercise Price, Vested/exercised	$ 3.32
Weighted Average Exercise Price, Canceled	$ 27.40
Weighted Average Exercise Price, Balance at March 31, 2012	$ 2.55		$ 2.89
Number of Options, Balance at January 1, 2012			1,901,000
Number of Options, Vested/exercised	754,000	[1]
Number of Options, Canceled	3,000
Number of Options, Balance	1,144,000	[2],[3]	1,901,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	0
Options outstanding, intrinsic value	$ 30
In-the-money' stock options (in number of options)	1,135,000
Stock options exercisable	1,080,000
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	$ 21.02
Weighted Average Grant Price, Vested/exercised	$ 12.72
Weighted Average Grant Price, Canceled	$ 14.20
Weighted Average Grant Price, Balance	$ 16.34		$ 13.64
Number of RSUs, Balance			3,497,000
Number of RSUs, Granted at fair market value	1,120,000
Number of RSUs, Vested/exercised	1,114,000	[1]
Number of RSUs, Canceled	67,000
Number of RSUs, Balance	3,436,000	[2],[3]	3,497,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Of Performance Based Stock Vested During Period	438,000
Number of performance based stock vested, intrinsic value	18
Options outstanding, intrinsic value	99
Aggregate unrecognized compensation expense related to awards	$ 32
Time-based restricted stock units outstanding	1,358,000
Number of performance-based and market-based stock units outstanding	2,078,000
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	637,000
Share-based compensation,RSUs eligible to vest	1,000
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	396,000
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

[1] During the nine months ended September 30, 2013, 438,000 market-vesting restricted stock units and 676,000 time-based restricted stock units vested. Stock options exercised during the nine months ended September 30, 2013 had an intrinsic value of $18 million.

[2] As of September 30, 2013, the Company’s outstanding RSUs had an aggregate intrinsic value of $99 million; aggregate unrecognized compensation expense related to RSUs amounted to $32 million; and the balance of RSUs at September 30, 2013, consists of 1,358,000 related to time-based awards and 2,078,000 related to market-vesting and performance-based awards. Approximately 1,000 time-based restricted stock units are eligible to vest in 2013, if applicable service criteria are satisfied.

[3] As of September 30, 2013, the Company’s outstanding stock options had aggregate intrinsic value of $30 million; there were 1,135,000 “in-the-money” stock options; and aggregate unrecognized compensation expense related to unvested stock options was immaterial. 1,080,000 stock options are exercisable as of September 30, 2013.