| **Employee Benefit Plans (Details) (USD $)In Thousands, unless otherwise specified**       | 12 Months Ended |
|--------------------------------------------------------------------------------------------|-----------------|
||
| **Compensation and Retirement Disclosure [Abstract]**                                      |            |   |
| Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay | 25.00%          |   |
| Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent              | 4.00%           |   |
| Defined Contribution Plan, Cost Recognized                                                 | $ 5             | $ 93 |
| Defined Contribution Plan Employers Matching, Contribution Vesting Period                  | 4 years         |   |

| X                                                                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the vesting period during which the employer contributes a matching contribution to the defined contribution plan.
+ References
No definition available.
+ Details**Name:**dlhc_DefinedContributionPlanEmployersMatchingContributionVestingPeriod**Namespace Prefix:**dlhc_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CompensationAndRetirementDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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=6414718&loc=d3e28014-114942
+ Details**Name:**us-gaap_DefinedContributionPlanCostRecognized**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.
+ References
No definition available.
+ Details**Name:**us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.
+ References
No definition available.
+ Details**Name:**us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |