STOCK-BASED COMPENSATION - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Stock based awards
Exercisable Stock Options, Weighted-Average Exercise Price (in dollars per share)	$ 46.66
Stock options
Stock based awards
Weighted-average remaining life of exercisable stock options	4 years 3 months 18 days
Exercisable stock options, aggregate intrinsic value (in dollars)	$ 47.9
Exercisable Stock Options, Weighted-Average Exercise Price (in dollars per share)	$ 46.66
Number of options vested or expected to vest (in shares)	3,284,246
Options vested or expected to vest, aggregate intrinsic value (in dollars)	$ 54.8
Options vested or expected to vest, weighted-average exercise price (in dollars per share)	$ 51.69
Unrecognized compensation cost (in dollars)	$ 6.6
Period over which unrecognized compensation cost is expected to be recognized	2 years 8 months 12 days
Total intrinsic value of options exercised (in dollars)	$ 6.3	$ 10.7	$ 100.9
Grant date fair value of shares vested (in dollars)	9.6	$ 8.1	$ 8.8
Restricted stock
Stock based awards
Unrecognized compensation cost (in dollars)	$ 19.2
Period over which unrecognized compensation cost is expected to be recognized	2 years 1 month 6 days
Restricted stock awards activity, shares
Unvested at the beginning of the period (in shares)	668,000	634,000	576,000
Granted (in shares)	294,000	275,000	230,000
Vested (in shares)	(256,000)	(214,000)	(157,000)
Forfeited (in shares)	(58,000)	(27,000)	(15,000)
Unvested at the end of the period (in shares)	648,000	668,000	634,000
Restricted stock awards activity, weighted average grant date fair value
Unvested at the beginning of the period (in dollars per share)	$ 67.03	$ 64.03	$ 55.17
Granted (in dollars per share)	58.25	68.83	79.67
Vested (in dollars per share)	64.75	60.80	54.08
Forfeited (in dollars per share)	63.65	64.45	67.92
Unvested at the end of the period (in dollars per share)	$ 64.24	$ 67.03	$ 64.03

Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Topic 718
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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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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 as a result of the occurrence of a terminating event.

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Amount by which the current fair value of the underlying stock exceeds the exercise price 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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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