COVER PAGE - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 17, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	000-50194
Entity Registrant Name	HMS HOLDINGS CORP
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	5615 High Point Drive
Entity Address, City or Town	Irving
Entity Address, State or Province	TX
Entity Tax Identification Number	11-3656261
Entity Address, Postal Zip Code	75038
City Area Code	214
Local Phone Number	453-3000
Title of 12(b) Security	Common Stock $0.01 par value
Trading Symbol	HMSY
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2.0
Common Stock, Shares Outstanding (in shares)		88,105,722
Documents Incorporated by Reference	Unless provided in an amendment to this Annual Report on Form 10-K, the information required by Part III is incorporated by reference to the registrant’s 2020 definitive proxy statement, to the extent stated herein. Such proxy statement or amendment will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2019.
Entity Central Index Key	0001196501
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false