Stockholders Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stockholders Equity Note [Line Items]
Preferred stock, authorized shares	500,000,000	500,000,000
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Common shares outstanding plus shares underlying outstanding stock awards, including all stock-based awards outstanding, including estimated forfeiture	483,000,000	476,000,000	470,000,000
2010 repurchase program authorized by Board of Directors	$ 2,000,000,000
2010 repurchase program authorized, remaining	763,000,000
Stock options outstanding	400,000	200,000	400,000
Net unrecognized compensation cost related to unvested stock-based compensation arrangements	2,200,000,000
Net unrecognized compensation cost related to unvested stock-based compensation arrangements, weighted average recognition period (in years)	1 year 2 months 12 days
Fair value of vested restricted stock units	$ 1,700,000,000	$ 1,400,000,000
Shares of common stock granted under the 401(k) savings plan	200,000	100,000
Common stock available for future issuance to employees	137,000,000
Minimum
Stockholders Equity Note [Line Items]
Restricted stock unit awards and stock options, vesting period	2 years
Maximum
Stockholders Equity Note [Line Items]
Restricted stock unit awards and stock options, vesting period	5 years