Stock-Based Compensation (Narrative)(Details) (USD $)	12 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period	5,436,000
Unvested shares outstanding	7,101,000	12,283,000
Total compensation expense for stock option and incentive shares plans	$ 121,000,000	$ 217,000,000	$ 54,000,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options granted at average of high and low prices of common stock on date of grant	100.00%
Amount of stock option vesting per year	one-third
Stock option expiration years from date of grant years	10
Share-based compensation arrangement by share-based payment award, number of shares available for grant	23,200,000
Weighted-average price of shares granted	$ 11.00	$ 8.51	$ 4.45
Cash received for stock options exercises	65,000,000	53,000,000	33,000,000
Options exercised, total intrinsic value	49,000,000	59,000,000	10,000,000
Actual tax benefit realized from tax deductions related to option exercises	16,000,000	4,000,000	7,000,000
Risk-free interest rate	1.90%	3.00%	2.40%
Expected dividend yield	2.60%	3.20%	4.20%
Expected volatility rate	25.00%	25.00%	22.00%
Expected life of option, years	7	7	7
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period	4,777,248
Common shares issued	2,841,534
Shares withheld for income tax	1,661,045
Paid in cash for share-based compensation	274,669
Award rights to receive common shares	5,367,146
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period	520,000
Common shares issued	299,990
Shares withheld for income tax	220,010
Vesting period, minimum, in years	three
Vesting period, maximum, in years	10
Unvested shares outstanding	1,733,956
Restricted Stock (Avocent Acquisition Related) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period		685,755
Common shares issued		467,452
Shares withheld for income tax		218,303
Unvested shares outstanding	115,956
Incentive Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	10,000,000
Total fair value of shares vested	276,000,000	42,000,000	3,000,000
Cash paid primarily for tax withholding	113,000,000	15,000,000	1,000,000
Stock Options And Incentive Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefits recognized in income statement for compensation arrangements	32,000,000	65,000,000	13,000,000
Unrecognized compensation cost related to non-vested awards granted	$ 170,000,000
Unrecognized compensation cost is expected to be recognized , weighted-average period, years	1.9
Restricted Stock For Non-Management Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	318,552
Common shares issued	15,656
Restricted stock units awarded	3,914

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Employee service share-based compensation, cash paid primarily to taxing authorities from exercise of incentive shares

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Paid in cash for share-based compensation.

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Percentage of options granted at average of high and low prices of common stock on date of grant.

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Restricted stock units awarded.

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Share based compensation arrangement by share based payment award rights to receive common shares .

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Stock option expiration years from date of grants.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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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.

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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 total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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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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The maximum vesting term over which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition.

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The minimum vesting term over which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition.

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

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The total fair value of equity-based awards 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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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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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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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The number of shares newly issued during the reporting period under the plan.

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For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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