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Retirement Benefit Plans - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of non-discretionary regular matching contribution of company | 100.00% |
Percentage of eligible compensation of deferral contribution, minimum | 1.00% |
Percentage of eligible compensation | 80.00% |
Percentage of eligible compensation of deferral contribution, maximum | 6.00% |
Matching contribution expense for defined contribution plan | $ 574 | $ 647
Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Employer contributions | $ 91 |

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- Definition Percentage of eligible compensation of deferral contribution, maximum. + References No definition available. + Details
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- Definition Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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