Stockholders' Equity (Narrative) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016
Payments for repurchases of common stock		$ 61,782	$ 125,542
Total unrecognized compensation cost related to non-vested stock-based compensation arrangements	$ 11,047	$ 11,047
Unrecognized compensation cost is expected to be recognized over a weighted-average period		2 years 1 month 6 days
Forfeiture rate, Board of Directors	0.00%	0.00%
Forfeiture rate, non-Board of Directors	9.00%	9.00%
Stock Options [Member]
Vested contractual term, in years		10 years
Vesting rate		25.00%
Vesting period, in years		4 years
Restricted Stock Award [Member]
Shares granted, Number of Shares	0	0
Restricted stock awards granted		24
Vesting period, in years		4 years
Service period for restricted stock award		4 years
2017 Plan [Member]
Stock-based compensation award conditionally awarded date		Oct. 03, 2016
Stock-based compensation plan effective date		Sep. 14, 2016
Number of stock shares authorized for grants	2,000	2,000
2016 Authorization [Member]
Authorized repurchase amount	$ 500,000	$ 500,000
Payments for repurchases of common stock		$ 61,229
Repurchase period in years		3 years
Purchases of treasury stock, number of shares		886
10b5-1 Plan [Member]
Authorized repurchase amount			125,000
Payments for repurchases of common stock			$ 125,000
Purchases of treasury stock, number of shares		350	2,635
10b-18 Plan [Member]
Purchases of treasury stock, number of shares		536

Unrecognized cost of unvested share-based compensation awards.

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The cash outflow to reacquire common stock during the period.

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Period 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, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Net number of non-option equity instruments granted to participants.

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Percentage of vesting of share-based compensation awards.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of stock repurchase plan authorized.

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Date stock-based compensation awards were conditionally awarded subject to stockholder approval.

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