Stockholders Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	490,000,000	483,000,000	476,000,000
2010 repurchase program authorized by Board of Directors	$ 2,000
2010 repurchase program authorized, remaining	$ 763
Stock options outstanding	200,000	400,000	200,000
Net unrecognized compensation cost related to unvested stock-based compensation arrangements	$ 3,100
Net unrecognized compensation cost related to unvested stock-based compensation arrangements, weighted average recognition period (in years)	1 year 1 month
Fair value of vested restricted stock units	$ 2,700	$ 1,700	$ 1,400
Shares of common stock granted under the 401(k) savings plan	200,000	200,000
Common stock available for future issuance to employees	130,000,000
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