Stockholders' Equity - Narrative (Details) - USD ($)	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018
Equity [Abstract]
Preferred stock outstanding (in shares)	0
Common stock authorized (in shares)	63,000,000	63,000,000
Common stock issued (in shares)	30,933,110	33,522,046
Authorized amount repurchase of common stock				$ 50,000,000
Common stock outstanding (in shares)	30,933,110	33,522,046
Aggregate repurchased value	$ (34,624,000)
Remaining availability repurchase amount	15,400,000
Value of redeemed stock	1,969,000	$ 3,378,000	$ 415,000
Dividends paid	$ 0	$ 0	$ 0
382 ownership limitation	4.95%

382 Ownership Limitation - stockholder ownership limited by the company's 382 rights agreement

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
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-Section S99
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-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of paid and unpaid cash, stock, and paid-in-kind (PIK) dividends declared, for example, but not limited to, common and preferred stock.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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- Definition

Equity impact of the value of stock bought back by the entity at the exercise price or redemption price.

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- Definition

Amount of stock repurchase plan authorized.

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- Definition

Amount remaining of a stock repurchase plan authorized.

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate 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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