Stock-Based Compensation (Stock Based Compensation Activity) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 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	$ 3.45
Weighted Average Exercise Price, Canceled	$ 27.40
Weighted Average Exercise Price, Balance at March 31, 2012	$ 2.49		$ 2.89
Number of Options, Balance at January 1, 2012			1,901,000
Number of Options, Vested/exercised	717,000	[1]
Number of Options, Canceled	3,000
Number of Options, Balance	1,181,000	[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	$ 31
In-the-money' stock options (in number of options)	1,172,000
Stock options exercisable	1,117,000
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	$ 20.99
Weighted Average Grant Price, Vested/exercised	$ 12.72
Weighted Average Grant Price, Canceled	$ 14.12
Weighted Average Grant Price, Balance	$ 16.30		$ 13.64
Number of RSUs, Balance			3,497,000
Number of RSUs, Granted at fair market value	1,117,000
Number of RSUs, Vested/exercised	1,104,000	[1]
Number of RSUs, Canceled	47,000
Number of RSUs, Balance	3,463,000	[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	436,000
Number of performance based stock vested, intrinsic value	17
Options outstanding, intrinsic value	100
Aggregate unrecognized compensation expense related to awards	$ 37
Time-based restricted stock units outstanding	1,374,000
Number of performance-based and market-based stock units outstanding	2,089,000
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	635,000
Share-based compensation,RSUs eligible to vest	9,000
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	395,000
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	3,000

[1] During the six months ended June 30, 2013, 436,000 market-vesting restricted stock units vested. Stock options exercised during the six months ended June 30, 2013 had an intrinsic value of $17 million.

[2] As of June 30, 2013, the Company’s outstanding stock options had aggregate intrinsic value of $31 million; there were 1,172,000 “in-the-money” stock options; and aggregate unrecognized compensation expense related to unvested stock options was immaterial. 1,117,000 stock options are exercisable as of June 30, 2013.

[3] As of June 30, 2013, the Company’s outstanding RSUs had an aggregate intrinsic value of $100 million; aggregate unrecognized compensation expense related to RSUs amounted to $37 million; and the balance of RSUs at June 30, 2013, consists of 1,374,000 related to time-based awards and 2,089,000 related to market-vesting and performance-based awards. Approximately 9,000 time-based restricted stock units and 3,000 market-vesting restricted stock units are eligible to vest in 2013, if applicable service criteria are satisfied.