Stock Compensation Plans (Details 4) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Stock Options
Closing stock price (in dollars per share)	$ 46.80
Aggregate intrinsic value of options outstanding	$ 136
Aggregate intrinsic value of exercisable options outstanding	129
Aggregate intrinsic value of stock options exercised	80	87	62
Cash received from the exercise of stock options	153	162	121
Tax benefit realized from the exercise of stock options	14	4	15
Unamortized deferred compensation expense	$ 263
Remaining weighted-average amortization period (in years)	2.0

Represents the entity's closing stock price.

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- Definition

Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph A240

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

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- Definition

The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

+ References

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- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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- Definition

The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of vested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

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- Definition

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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- Definition

The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

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