Share Based Compensation (RSU Activity) (Details) - $ / shares	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Vested and expected to vest (shares)	3,189,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average exercise price, vested and expected to vest (in dollars per share)	$ 13.79
Forfeited (shares)	(67,000)	(172,000)	(511,000)
Weighted average grant date fair value, forfeited (in dollars per share)	$ 6.82	$ 4.94	$ 4.38
Share-based Compensation Arrangement by Share-based Payment Award, Other Share Increase (Decrease)	(1,000)	(6,000)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price	$ 16.63	$ 20.60
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding at beginning of the period (shares)	750,000	2,002,000
Granted (shares)	731,000	394,000
Outstanding at the end of the period (in shares)	1,209,000	750,000	2,002,000
Vested and expected to vest (shares)	1,165,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, nonvested, equity instruments other than options, beginning of the period (in dollar per share)	$ 17.86	$ 17.45
Weighted average grant date fair value, granted (in dollars per share)	25.98	23.05
Weighted average grant date fair value, nonvested, equity instruments other than options, end of the period (in dollar per share)	22.77	$ 17.86	$ 17.45
Weighted average exercise price, vested and expected to vest (in dollars per share)	$ 22.67
Forfeited (shares)	(25,000)	(91,000)
Vested and expected to vest (shares)	(240,000)	(1,555,000)
Weighted average grant date fair value, vested and expected to vest (in dollars per share)	$ 17.55	$ 18.79
Weighted average grant date fair value, forfeited (in dollars per share)	$ 20.31	$ 15.35
Share-based Compensation Arrangement by Share-based Payment Award, Other Share Increase (Decrease)	(7,000)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price	$ 21.22
Special RSU
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Granted (shares)	469,000
Outstanding at the end of the period (in shares)	469,000
Vested and expected to vest (shares)	426,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, granted (in dollars per share)	$ 16.92
Weighted average grant date fair value, nonvested, equity instruments other than options, end of the period (in dollar per share)	16.92
Weighted average exercise price, vested and expected to vest (in dollars per share)	$ 16.92

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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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-Publisher FASB
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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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- Definition

Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Other than shares newly issued, the number of additional shares issued (for example, a stock split) or canceled (for example, to correct a share issuance), during the period under the plan.

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Weighted average price at which grantees could acquire or could have acquired the underlying shares with respect to any other type of change in shares reserved for issuance.

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Number of non-vested options forfeited.

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Weighted average grant-date fair value of non-vested options forfeited.

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