Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2017
Accounting Policies [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued amended guidance for revenue recognition. Subsequently, the FASB issued an amendment to defer for one year the effective date of the new guidance on revenue recognition, as well as issued additional clarifying amendments. The new guidance outlines a single comprehensive model for entities to use 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, the guidance requires improved disclosure to help the users of the financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. The new guidance supersedes most current revenue recognition guidance, including industry-specific guidance, and is now effective commencing with our 2018 fiscal year. The guidance allows either a full retrospective or modified retrospective transition method. The Company believes that the impact of adoption will be immaterial to the financial statements. In June 2014, the FASB issued guidance related to accounting for share-based payments for certain performance stock awards. In March 2016, the FASB issued updated guidance intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The amendments in this update affect all entities that issue share-based payment awards to their employees. For public business entities, the amendments in this update are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company has adopted this guidance and concluded that it will not significantly affect the Company. In September 2015, the FASB issued guidance regarding business combinations for which the accounting is incomplete by the end of the reporting period in which the combination occurs, and during the measurement period have an adjustment to provisional amounts recognized. To simplify the accounting for adjustments made to provisional amounts recognized in a business combination, the amendments in this update eliminate the requirement to retrospectively account for those adjustments. The amendments in this update are effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendments should be applied prospectively to adjustments to provisional amounts that occur after the effective date of this update, with earlier application permitted for financial statements that have not been issued. Refer to Note 4 for the impact of the adoption of this guidance. In February 2016, the FASB issued new accounting guidance related to leases. This update, effective for the Company beginning October 1, 2019, will replace existing guidance in GAAP and will require lessees to recognize lease assets and lease liabilities on the balance sheet for all lease and disclose key information about leasing arrangements. When implemented, lessees and lessors will be required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. As shown in Note 10, the Company currently has approximately $4.3 million of lease obligations that would be evaluated as the implementation of this guidance becomes effective.
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 and intangible assets, valuation allowances established against accounts receivable and deferred tax assets, measurement of loss development on workers’ compensation claims, and fair value of derivatives. We evaluate these estimates and judgments on an ongoing basis and base our estimates on historical experience, current and expected future outcomes, third-party evaluations and various other assumptions that we believe are reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. We revise material accounting estimates if changes occur, such as more experience is acquired, additional information is obtained, or there is new information on which an estimate was or can be based. Actual results could differ from those estimates. In particular, a material reduction in the fair value of goodwill could have a material adverse effect on the Company’s financial position and results of operations. We account for the effect of a change in accounting estimate during the period in which the change occurs.
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. We generally operate as a prime contractor, but have also entered into contracts as a subcontractor. The recognition of revenue from fixed rates is based upon objective criteria that generally do not require significant estimates. DLH recognizes and records revenue on government contracts when it is realized, or realizable, and earned. DLH considers these requirements met 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. Business Combinations In accordance with Accounting Standards Codifications 805, "Business Combinations" ("ASC 805") the Company records acquisitions under the purchase method of accounting, under which the acquisition purchase price is allocated to the assets acquired and the liabilities assumed based upon the respective fair values. The Company utilizes some estimates and in some instances, may retain the services of an independent third-party valuation firm to assist in determining the fair values of assets acquired, liabilities, assumed, and contingent considerations granted. Such estimates and valuation require the Company to make significant assumptions. These assumptions may include projections of future events and operating performance. Fair Value of Financial Instruments The carrying amounts of the Company's cash and cash equivalents, accounts receivable, unbilled revenues, accrued expenses, accrued earn outs payable, 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 We have used the acquisition method of accounting for the Danya transaction, whereby the assets acquired and liabilities assumed are recognized based upon their estimated fair values at the acquisition date. The fair values of assets acquired and liabilities assumed are based on the information that was available as of the acquisition date. The Company believes the information provides a reasonable basis for estimating the fair values of assets acquired and liabilities assumed. The Company finalized the fair values as of December 31, 2016. On the basis of the estimated assets acquired, the Company amortized $0.4 million and $1.0 million for the three and nine months ended June 30, 2017, respectively. 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, 2016, we performed a goodwill impairment evaluation on the year-end carrying value of approximately $35 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, 2016. For the nine months ended June 30, 2017, the Company determined that 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.
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. We had no uncertain tax positions at either June 30, 2017 or September 30, 2016. We report interest and penalties as a component of income tax expense. In the fiscal quarters ended June 30, 2017 and June 30, 2016, we recognized no interest and no penalties related to income taxes.
Long-lived Assets	Long Lived Assets The Company acquired certain long lived intangibles assets as part of the acquisition of Danya. These assets are estimated at a fair value and amortized on a straight-line basis over their assessed useful lives. The assessed useful lives of the assets are 10 years.
Stock-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 (Loss) 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 (loss) available to common shareholders by the weighted average number of basic common shares outstanding, adjusted to reflect potentially dilutive securities. Diluted earnings per share is calculated using the treasury stock method. Reclassification We present financial statements consistent with a consolidation model for all entities. In connection with ensuring that presentation among the quarters was consistent, we reclassified an amount totaling $0.1 million in our income statement from general and administrative expense to direct expenses.

Disclosure of accounting policy for cash and cash equivalents, including the policy for determining which items are treated as cash equivalents. Other information that may be disclosed includes (1) the nature of any restrictions on the entity's use of its cash and cash equivalents, (2) whether the entity's cash and cash equivalents are insured or expose the entity to credit risk, (3) the classification of any negative balance accounts (overdrafts), and (4) the carrying basis of cash equivalents (for example, at cost) and whether the carrying amount of cash equivalents approximates fair value.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

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