Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2011
Stock Option [Member]
Stock Option Activity [Abstract]
Stock options, shares outstanding at January 1, 2011	9,815
Stock options, shares granted	618
Stock options, shares exercised	(2,659)
Stock options, shares forfeited or expired	(40)
Stock options, shares outstanding at June 30,2011	7,734
Stock options, shares vested or expected to vest at June 30, 2011	7,645
Stock options, share options exercisable at June 30, 2011	6,077
Stock options weighted-average exercise price, outstanding at January 1, 2011	$ 44.77
Stock options weighted-average exercise price granted	$ 93.60
Stock options weighted-average exercise price exercised	$ 37.98
Stock options weighted-average exercise price forfeited or expired	$ 63.11
Stock options weighted-average exercise price, outstanding at June 30, 2011	$ 50.91
Stock options weighted-average exercise price, vested or expected to vest at June 30, 2011	$ 50.71
Stock options weighted-average exercise price, options exercisable at June 30, 2011	$ 46.12
Stock options weighted-average remaining contractual term in years, outstanding at January 1, 2011	5.2
Stock options weighted-average remaining contractual term in years, outstanding at June 30, 2011	5.7
Stock options weighted-average remaining contractual term in years, vested or expected to vest at June 30, 2011	5.7
Stock options weighted-average remaining contractual term in years, options exercisable at June 30, 2011	4.9
Stock options aggregate intrinsic value, outstanding at January 1, 2011	$ 470
Stock options aggregate intrinsic value, outstanding at June 30, 2011	414
Stock options aggregate intrinsic value, vested or expected to vest at June 30, 2011	410
Stock options aggregate intrinsic value, options exercisable at June 30, 2011	354
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation expense	25
Expected weighted average period (in years) of nonvested stock options to be recognized	1.2
Retention Awards [Member]
Awards Activity [Abstract]
Awards, shares nonvested at January 1, 2011	2,638
Awards, shares granted	528
Awards, shares vested	(527)
Awards, shares forfeited	(54)
Awards, shares nonvested at June 30, 2011	2,585
Awards weighted-average grant-date fair value, nonvested at January 1, 2011	$ 54.01
Awards weighted-average grant-date fair value, granted	$ 93.68
Awards weighted-average grant-date fair value, vested	$ 48.58
Awards weighted-average grant-date fair value, forfeited	$ 57.46
Awards weighted-average grant-date fair value, nonvested at June 30, 2011	$ 63.15
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation expense	90
Expected weighted average period (in years) of nonvested stock options to be recognized	2
Performance Retention Awards [Member]
Awards Activity [Abstract]
Awards, shares nonvested at January 1, 2011	1,151
Awards, shares granted	376
Awards, shares vested	(194)
Awards, shares forfeited	(116)
Awards, shares nonvested at June 30, 2011	1,217
Awards weighted-average grant-date fair value, nonvested at January 1, 2011	$ 53.93
Awards weighted-average grant-date fair value, granted	$ 89.87
Awards weighted-average grant-date fair value, vested	$ 60.20
Awards weighted-average grant-date fair value, forfeited	$ 59.64
Awards weighted-average grant-date fair value, nonvested at June 30, 2011	$ 63.49
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation expense	$ 45
Expected weighted average period (in years) of nonvested stock options to be recognized	1.6

The weighted average period between the balance-sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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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.

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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.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The weighted average period between the balance sheet date and expiration for all vested portions of options outstanding and currently exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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Net number of share options (or share units) granted during the period.

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The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

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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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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The weighted average period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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As of the balance sheet date, the total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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The weighted-average period between the balance sheet date and expiration date for fully vested and expected to vest options outstanding, which may be expressed in a decimal value for number of years.

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Number of share options (or share units) exercised during the current period.

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