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Capital Stock (Details) - shares	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Outstanding Shares [Roll Forward]
Shares outstanding	158,590,383	161,693,051	160,497,841
Exercised stock options	851,628	905,834	270,599
Exercise of employee stock purchase plan	150,669	150,174	218,475
Vesting of restricted stock units, net of shares withheld for taxes	232,875	262,488	370,138
Treasury Stock, Shares, Acquired	(6,475)
Shares outstanding	157,332,121	158,590,383	161,693,051
Stock repurchased under buyback program	(2,573,475)	(4,581,227)
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		160,063
Performance Shares [Member]
Outstanding Shares [Roll Forward]
Settlement of performance-based restricted stock units, net of shares withheld for taxes	146,061	263,410
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	86,516		335,998

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Outstanding Shares [Roll Forward]

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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- Definition

The number of restricted shares issued as compensation, net of shares for the payment of withholding taxes. This element is to be used only if shares are used in lieu of cash to satisfy all or a portion of withholding taxes.

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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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Number of share instruments newly issued under a share-based compensation plan.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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

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Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Number of shares that have been repurchased during the period and are being held in treasury.

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