Net Income Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
NUMERATOR:
Net income	$ 59	$ 98
DENOMINATOR:
Weighted-average shares outstanding, basic	725	771
Dilutive effect of Employee stock options and restricted stock units	2	1
Adjusted weighted-average shares outstanding, diluted	727	772
NET INCOME PER SHARE:
Basic (in dollars per share)	$ 0.08	$ 0.13
Diluted (in dollars per share)	$ 0.08	$ 0.13
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive amounts excluded from calculations:	17	44
5.25% convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive amounts excluded from calculations:	6	6

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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