| **Commitment and Contingencies (Details) (USD $)**                                                        |           |           | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------|-----------|-----------|-----------------|
||
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                          |      |      |            |   |
| Estimated additional indirect costs and fees associated with contract modification pending final approval |      |      | $ 400,000       | $ 600,000 |
| Accrued workers compensation expense                                                                      | $ 767,000 | $ 563,000 |            |   |

| X                                                                                                                                                                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the estimated additional indirect costs and fees associated with a contract modification pending final approval.
+ References
No definition available.
+ Details**Name:**dlhc_AdditionalIndirectCostsAndFeesEstimatedAmountPendingApproval**Namespace Prefix:**dlhc_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesAndLoansReceivableLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).
+ References
No definition available.
+ Details**Name:**us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |