Amount of cost for defined contribution plan.

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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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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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Namespace Prefix:	us-gaap_
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- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

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Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Contribution Plan Disclosure [Line Items]
Matching contributions, amount	$ 1.4	$ 1.4	$ 1.7
Defined contribution plan
Defined Contribution Plan Disclosure [Line Items]
Maximum annual contribution per employee percentage	25.00%
Defined contribution plan \| Full Employer Match
Defined Contribution Plan Disclosure [Line Items]
Employers percent of matching contributions	100.00%
Percent of employees' gross pay for employer match	3.00%
Defined contribution plan \| Half Employer Match
Defined Contribution Plan Disclosure [Line Items]
Employers percent of matching contributions	50.00%
Percent of employees' gross pay for employer match	2.00%