| **ORGANIZATION AND BUSINESS: (Details)**                                                          | 3 Months Ended |
|---------------------------------------------------------------------------------------------------|----------------|
||
| **Organization, Consolidation and Presentation of Financial Statements [Abstract]**               |           |
| Minimum period for which entity has provided professional services to the U.S. Government (years) | 25 years       |
| Number of employees (employee)                                                                    | 1,200          |
| Minimum number of locations in which entity operates (location)                                   | 25             |
| Number of integrated business areas of DLH Solutions (business area)                              | 3              |

| X                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of persons employed by the Entity
+ References
No definition available.
+ Details**Name:**dei_EntityNumberOfEmployees**Namespace Prefix:**dei_**Data Type:**xbrli:decimalItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the number of integrated business areas of the entity.
+ References
No definition available.
+ Details**Name:**dlhc_EntityNumberOfIntegratedBusinessAreas**Namespace Prefix:**dlhc_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the period for which the entity has provided professional services to U.S. Government.
+ References
No definition available.
+ Details**Name:**dlhc_EntityPeriodOfProfessionalServicesMinimum**Namespace Prefix:**dlhc_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the minimum number of locations the entity operates in as of the balance sheet date.
+ References
No definition available.
+ Details**Name:**dlhc_NumberOfLocationsInWhichEntityOperatesMinimum**Namespace Prefix:**dlhc_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |