Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of DLH and its subsidiaries, all of which are wholly owned. All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles and with the instructions to Form 10-K, Regulation S-X, and Regulation S-K.
Reclassifications	Certain reclassifications have been made to the prior year’s consolidated financial statements to conform to the current year presentation.
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued amended revenue recognition guidance, including subsequent amendments, which was summarized into ASC 606, "Revenue from Contracts with Customers". ASC 606 affects any entity using U.S. GAAP that either enters into contracts with customers to transfer goods or services unless those contracts are within the scope of other standards. The new guidance outlines a single comprehensive model for entities to apply in accounting for revenue arising from contracts with customers. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additionally, this guidance required improved disclosures to help users of the financial statements better understand the nature, timing, and potential uncertainty of revenue that is recognized. To achieve that core principle, an entity should apply the following steps: Step 1: Identify the contract(s) with a customer. Step 2: Identify the performance obligations in the contract. Step 3: Determine the transaction price. Step 4: Allocate the transaction price to the performance obligations in the contract. Step 5: Recognize revenue when (or as) the entity satisfies a performance obligation. In addition, the FASB amended ASC 340-40 to provide guidance on costs to obtain contracts with customers. For a public entity, the amendments in this ASU are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, using either a full retrospective approach or a modified approach. The Company adopted the standard on a modified retrospective basis on October 1, 2018, whereby the cumulative effect of applying the standard was recognized through shareholders’ equity on the date of adoption. In interim periods of our fiscal year ending September 30, 2019, we will be required to provide additional disclosures regarding the amount by which each financial statement line item is affected in the current reporting period by the application of this ASU as compared to the guidance that was in effect before the change. Upon adoption on October 1, 2018, the Company recorded a net increase to shareholders’ equity of approximately $0.1 million. This amount related principally to the proportional recognition of revenue on fixed price services contracts. As part of our implementation process, we reviewed representative contracts within each revenue stream, updated accounting policies and procedures, and internal controls over financial reporting. We evaluated the cumulative equity adjustment and updated financial reporting and footnote disclosures as required by the new standard. We have substantially completed our implementation process in 2018. We do not expect that ASC 606 will have a material impact to our pattern of revenue recognition. Revenue for our current contract base is predominantly (95%) recognized on a time and materials basis, as the performance obligation is satisfied. An additional 3% of our revenue is derived from cost plus fixed fee contract arrangements, under which revenue is recognized as reimbursement of costs incurred in satisfaction of performance obligations, plus a proportional share of the fee earned. The final 2% of our revenue is derived from short-term (one year or less) fixed price services contracts. Revenue from fixed price services contracts is currently recognized evenly throughout the period of performance, but under ASC 606 we will estimate satisfaction of performance obligations on a proportional basis using a cost-to-cost input method. The adoption of ASC 340-40 will require capitalization of certain costs to obtain and fulfill a contract, with amortization of those deferred costs over the contract’s period of performance as underlying performance obligations are satisfied. In February 2016, the FASB issued new accounting guidance related to leases. This new accounting guidance is intended to improve financial reporting about leasing transactions. This accounting standard will require organizations that lease assets referred to as “Lessees” to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. An organization is to provide disclosures designed to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements concerning additional information about the amounts recorded in the financial statements. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than twelve months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. However, unlike current GAAP which requires only capital leases to be recognized on the balance sheet, new guidance will require both types of leases (i.e., operating and finance) to be recognized. Finance leases will be accounted for in substantially the same manner as capital leases. Public companies will be required to adopt the new leasing standard for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted for all companies and organizations. ASU 2018-11 allows companies to elect not to recast comparative period presented when transitioning to ASC 842. The Company does not have a large portfolio of leases and is not likely to see a significant increase in balance sheet assets and liabilities resulting from the adoption of this new lease accounting guidance. As shown in Note 10, the Company currently has approximately $2.8 million of active lease commitments that will be evaluated as the implementation of this new lease accounting guidance becomes effective. In August 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-15, Statement of Cash Flows (Topic 230). This amendment provides guidance on the presentation and classification of specific cash flow items to improve consistency within the statement of cash flows. The Company adopted ASU No. 2016-15 on October 1, 2017 and its adoption did not have a material impact on the Company’s consolidated cash flows. In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment, which simplifies the accounting for goodwill impairments by eliminating step two from the goodwill impairment test. Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss shall be recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to that reporting unit. ASU 2017-04 also clarifies the requirements for excluding and allocating foreign currency translation adjustments to reporting units related to an entity's testing of reporting units for goodwill impairment and clarifies that an entity should consider income tax effects from any tax-deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new standard is effective for fiscal years beginning January 1, 2020 for both interim and annual reporting periods. The Company is currently assessing the potential impact of the adoption of ASC 2017-04 on its consolidated financial statements. In May 2017, the FASB issued Accounting Standards Update ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. ASC 2017-09 provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The Company will adopt this standard in the first quarter of fiscal 2019 and its adoption is not expected to have a material impact on the Company’s consolidated financial statements. In July 2017, the FASB issued new accounting guidance related to certain equity-linked financial instruments with down round features, such as warrants. The guidance provides for a scope exception from derivative accounting if the instruments qualify for equity classification. Should the instruments qualify for equity classification, they would no longer be considered liabilities subject to fair value measurement at each reporting period. This update is effective for the Company as of its fiscal year beginning October 1, 2019, with early adoption permitted. The Company has elected to adopt the provisions of this ASU in the current fiscal year. See Note 8. Common Stock Warrants. In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting, which simplifies the accounting for share-based payments granted to nonemployees for goods and services. Under the ASU, most of the guidance on such payments to nonemployees would be aligned with the requirements for share-based payments granted to employees. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted, but no earlier than an entity’s adoption date of Topic 606. The Company is currently assessing the potential impact on the Company’s consolidated financial statements and related disclosures.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates include valuation of goodwill, measurement of prepaid workers’ compensation, valuation allowances established against deferred tax assets, measurement of contingent liabilities, accounts payable, workers’ compensation claims, and accrued expenses and the valuation of derivative financial instruments associated with debt agreements. In addition, the Company estimates overhead charges and allocates such charges throughout the year. Actual results could differ from those estimates. In particular, a material reduction in the fair value of goodwill would have a material adverse effect on the Company’s financial position and results of operations.
Revenue Recognition	Revenue Recognition DLH’s revenue is derived from professional and other specialized service offerings to US Government agencies through a variety of contracts, some of which are fixed-price in nature and/or sourced through Federal Supply Schedules administered by the General Services Administration (“GSA”) at fixed unit rates or hourly arrangements. Revenue on time and materials contracts is recognized based on hours performed times the applicable hourly rate, plus materials and other direct costs incurred on the contract. Revenue on fixed fee for service contracts is recognized over the period of performance of the contract. Revenue on cost reimbursable contracts is recognized equal to allowable costs incurred, plus a ratable portion of the applicable fee. DLH recognizes and records revenue on government contracts when: (a) persuasive evidence of an arrangement exists; (b) the services have been delivered to the customer; (c) the sales price is fixed or determinable and free of contingencies or significant uncertainties; and (d) collectibility is reasonably assured.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of the Company's cash and cash equivalents, accounts receivable, unbilled receivables, accrued expenses, and accounts payable approximate fair value due to the short-term nature of these instruments. The fair values of the Company's debt instruments approximate fair value because the underlying interest rates approximate market rates that the Company could obtain for similar instruments at the balance sheet dates.
Goodwill and other intangible assets	Goodwill and other intangible assets DLH continues to review its goodwill and other intangible assets for possible impairment or loss of value at least annually or more frequently upon the occurrence of an event or when circumstances indicate that a reporting unit’s carrying amount is greater than its fair value. At September 30, 2018, we performed a goodwill impairment evaluation on the year-end carrying value of approximately $26 million. We performed both a qualitative and quantitative assessment of factors to determine whether it was necessary to perform the goodwill impairment test. Based on the results of the work performed, the Company has concluded that no impairment loss was warranted at September 30, 2018, as no change in business conditions occurred which would have a material adverse effect on the valuation of goodwill. Notwithstanding this evaluation, factors including non-renewal of a major contract or other substantial changes in business conditions could have a material adverse effect on the valuation of goodwill in future periods and the resulting charge could be material to future periods’ results of operations. There were no impairments during the year ended September 30, 2017.
Long Lived Assets	Long Lived Assets Equipment and improvements are stated at cost. Depreciation and amortization are provided using the straight-line method over the estimated useful asset lives (3 to 7 years) and the shorter of the initial lease term or estimated useful life for leasehold improvements.
Income Taxes	Income Taxes DLH accounts for income taxes in accordance with the liability method, whereby deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities, using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are reflected on the consolidated balance sheet when it is determined that it is more likely than not that the asset will be realized. This guidance also requires that deferred tax assets be reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax asset will not be realized. We account for uncertain tax positions by recognizing the financial statement effects of a tax position only when, based upon the technical merits, it is "more-likely-than-not" that the position will be sustained upon examination.
Share-based Equity Compensation	Stock-based Equity Compensation The Company uses the fair value-based method for stock-based equity compensation. Options issued are designated as either an incentive stock or a non-statutory stock option. No option may be granted with a term of more than 10 years from the date of grant. Option awards may depend on achievement of certain performance measures determined by the Compensation Committee of our Board. Shares issued upon option exercise are newly issued common shares. All awards to employees and non-employees are recorded at fair value on the date of the grant and expensed over the period of vesting. The Company uses a binomial option pricing model to estimate the fair value of each stock option at the date of grant. Any consideration paid by the option holders to purchase shares is credited to capital stock.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. We maintain cash balances at financial institutions that are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. Deposits held with financial institutions may exceed the $250,000 limit.
Earnings per Share	Earnings per Share Basic earnings per share is calculated by dividing income available to common shareholders by the weighted average number of common stock outstanding and restricted stock grants that vested or are likely to vest during the period. Diluted earnings per share is calculated by dividing income available to common shareholders by the weighted average number of basic common shares outstanding, adjusted to reflect potentially dilutive securities such as common stock warrants and stock options. Diluted earnings per share is calculated using the treasury stock method.