| **ORGANIZATION AND BUSINESS: (Details)**                                                  | 12 Months Ended |
|-------------------------------------------------------------------------------------------|-----------------|
||
| **Organization, Consolidation and Presentation of Financial Statements [Abstract]**       |            |
| Minimum period for which entity has provided professional services to the U.S. Government | 25 years        |
| Number of employees                                                                       | 1,100           |
| Minimum number of locations in which entity operates                                      | 25              |
| Number of integrated business areas of DLH Solutions                                      | 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 |