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Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017 | May 20, 2019 | Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted |  | 283,195 |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding |  | 21,750 |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price |  | $ 6.35 |  |  |  |
Options exercised, shares |  | 22,500 | 1,500 | 33,750 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 6.39 | $ 6.39 | $ 6.42 | $ 6.43 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price |  | $ 6.35 | $ 6.39 | $ 6.42 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 44,250 | 44,250 | 45,750 | 79,500 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |  | 21,750 | 44,250 | 45,750 |  |
Restricted Stock or Unit Expense |  | $ 3,800 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  | (140,668) | (31,409) |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number | 0 | 0 | 140,668 | 174,334 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number |  | 283,195 | 0 | 140,668 |  |
Common Stock, Shares Authorized |  | 100,000,000 | 100,000,000 |  |  |
Treasury Stock, Shares, Acquired |  | 467,819 | 100,627 |  |  |
Shares, Issued |  | 22,500 |  |  |  |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price |  | $ 6.43 | $ 7.21 | $ 6.46 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |  | $ 254 | $ 292 |  |  |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount |  | $ 3,024 |  |  |  |
Common Stock, Capital Shares Reserved for Future Issuance |  | 824,676 |  |  |  |
Stock Repurchase Program, Number of Shares Authorized to be Repurchased |  | 1,500,000 |  |  | 1,000,000.0 |
Treasury Stock Acquired, Average Cost Per Share |  | $ 17.34 | $ 15.41 |  |  |
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation |  | 97,003 | 32,832 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period |  |  |  | (2,257) |  |
Equity Option [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  | $ 23 |  |
Restricted Stock [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value |  | $ 0 | $ 2,201 | 460 |  |
Share-based Payment Arrangement, Expense |  | 776 | 256 | 538 |  |
Phantom Share Units (PSUs) [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  | $ 300 | $ 189 | $ 167 |  |
Shares, Outstanding |  | 210,386 |  |  |  |
Performance Based Phantom Shares [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Shares, Issued |  | 264,815 |  |  |  |
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited |  | 97,985 |  |  |  |
Shares, vested |  | 3,991 |  |  |  |
Share-based Payment Arrangement, Expense | $ 581 | $ 1,151 |  |  |  |
Shares, Outstanding |  | 162,840 |  |  |  |
Treasury Stock [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Options exercised, shares |  | 22,500 | 1,500 | 33,750 |  |
Treasury Stock, Shares, Acquired |  | 564,822 | 133,459 | 152,860 |  |
Shares, Issued |  | 884,518 | 843,993 | 712,554 |  | 592,990
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period |  | 216,679 |  |  |  |
Share-based Payment Arrangement, Employee [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period |  |  | 1,500 |  |  |
Share-based Payment Arrangement, Nonemployee [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Shares, Issued |  | 1,923 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period |  |  | 520 |  |  |
Share Repurchase Program [Domain] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Treasury Stock, Shares, Acquired |  | 467,819 |  |  |  |
Equity Incentive Plan [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Common Stock, Shares Authorized |  | 3,000,000.0 |  |  |  |
Chief Executive Officer [Member] | Restricted Stock [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period |  | 283,195 |  |  |  |
$5.76 [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding |  | 13,000 |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term |  | 3 years 6 months 29 days |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price |  | $ 5.76 |  |  |  |
$7.27 [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding |  | 1,000 |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term |  | 5 years 3 months 14 days |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price |  | $ 7.27 |  |  |  |
$7.21 [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding |  | 7,750 |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term |  | 5 years 4 months 2 days |  |  |  |
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price |  | $ 7.21 |  |  |  |

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