Business and Summary of Significant Accounting Policies	9 Months Ended
Business and Summary of Significant Accounting Policies	Sep. 30, 2020
Accounting Policies [Abstract]
Business and Summary of Significant Accounting Policies	Business and Summary of Significant Accounting Policies (a) Business The terms “HMS,” “Company,” “we,” “us,” and “our” refer to HMS Holdings Corp. and its consolidated subsidiaries unless the context clearly indicates otherwise. HMS is an industry-leading provider of cost containment and analytical solutions in the healthcare marketplace. Our mission is to make healthcare work better for everyone. We use data, technology and analytics to deliver payment accuracy and population health management solutions that help healthcare organizations reduce costs, improve health outcomes and enhance consumer experiences. We currently operate as one business segment with a single management team that reports to the Chief Executive Officer. The Consolidated Financial Statements and accompanying Notes in this Form 10-Q are unaudited. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The results reported in these unaudited Consolidated Financial Statements are not necessarily indicative of the results that may be expected for any subsequent interim period or the entire year. These unaudited Consolidated Financial Statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (“2019 Form 10-K”). The consolidated balance sheet as of December 31, 2019 included herein was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. The preparation of the Company’s unaudited Consolidated Financial Statements requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities at the date of the unaudited Consolidated Financial Statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates. These estimates and assumptions were considered and made in context with the information reasonably available to the Company and the unknown future impacts of the novel coronavirus (COVID-19) as of September 30, 2020 and through the date of this Form 10-Q. The statements include all adjustments (which include only normal recurring adjustments, except as disclosed) that management considers necessary to present a fair statement of the Company’s results for such interim periods. These unaudited Consolidated Financial Statements include HMS accounts and transactions and those of the Company’s wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. (b) Summary of Significant Accounting Policies There have been no material changes to the Company’s significant accounting policies that are referenced in the 2019 Form 10-K. Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments – Credit Losses (“ASU 2016-13”). ASU 2016-13 introduces the current expected credit losses methodology for estimating allowances for credit losses. ASU 2016-13 applies to all financial instruments carried at amortized cost and off-balance-sheet credit exposures not accounted for as insurance, including loan commitments, standby letters of credit, and financial guarantees. The new accounting standard does not apply to trading assets, loans held for sale, financial assets for which the fair value option has been elected, or loans and receivables between entities under common control. ASU 2016-13 is effective for public entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company adopted this guidance on January 1, 2020. When developing an estimate of the Company's expected credit losses, the Company considers all relevant information regarding the collectability of cash flows including historical information, customers' credit history and current financial conditions, industry trends and reasonable and supportable forecasts of future economic conditions over the contractual life of the receivable. The adoption of this guidance did not have a material effect on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15"). The standard aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal use software. ASU 2018-15 is effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company adopted this guidance on January 1, 2020. The adoption of this guidance did not have a material effect on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements ("ASU 2018-13"). The objective of the ASU is to improve the disclosures related to fair value measurement by removing, modifying, or adding disclosure requirements related to recurring and non-recurring fair value measurements. ASU 2018-13 is effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company adopted this guidance on January 1, 2020. The adoption of this guidance did not have a material effect on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"). The guidance eliminates certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period, and the recognition of deferred tax liabilities for outside basis differences related to changes in ownership of equity method investments and foreign subsidiaries. The guidance also simplifies aspects of accounting for franchise taxes and enacted changes in tax laws or rates, and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period for which financial statements have not been issued. This guidance is not expected to have a material impact on the Company’s financial position, results of operations or internal control framework. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04"). The objective of ASU 2020-04 is to provide optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. The guidance is effective for all entities as of March 12, 2020 through December 31, 2022. The Company is evaluating the impact, but does not expect this guidance to have a material impact on the Company’s consolidated financial statements.