PROFIT SHARING PLAN (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016
PROFIT SHARING PLAN
Employee's maximum voluntary contribution as percentage of their compensation	100.00%
Percentage of employer's contribution matching first 4 percent of employee's compensation	50.00%
Percentage of first portion of employee's compensation eligible for employer's matching contribution	4.00%
Percentage of employer's contribution matching next 2 percent of employee's compensation	100.00%
Percentage of second portion of employee's compensation eligible for employer's matching contribution	2.00%
Maximum matching percentage of employee compensation	4.00%
Company's matching contributions to the profit sharing plan (net of employee forfeitures)	$ 0.7	$ 0.7

Represents the first level of employee contributions (percentage of compensation) which are matched by the employer.

No definition available.

Name:	dit_DefinedContributionPlanEmployerMatchEmployeeContributionLevelOne
Namespace Prefix:	dit_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the second level of employee contributions (percentage of compensation) which are matched by the employer.

+ References

No definition available.

+ Details

Name:	dit_DefinedContributionPlanEmployerMatchEmployeeContributionLevelTwo
Namespace Prefix:	dit_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the employer matching contribution of the first level of employee contributions.

+ References

No definition available.

+ Details

Name:	dit_DefinedContributionPlanEmployerMatchLevelOne
Namespace Prefix:	dit_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the employer matching contribution of the second level of employee contributions.

+ References

No definition available.

+ Details

Name:	dit_DefinedContributionPlanEmployerMatchLevelTwo
Namespace Prefix:	dit_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum percentage of employee compensation, by the terms of the plan, that the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	dit_DefinedContributionPlanMaximumEmployeeContributionAsPercentageOfCompensation
Namespace Prefix:	dit_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	dit_ProfitSharingPlanDisclosureAbstract
Namespace Prefix:	dit_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ 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

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration