Note 5 - Acquisitions (Details Textual) - Eliza Holding Corp [Member] $ in Millions	Apr. 17, 2017 USD ($)
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Payments to Acquire Businesses, Gross	$ 171.6
Business Acquisition, Funding Source, Cash on Hand, Percentage	75.00%
Business Acquisition, Funding Source, Existing Credit Line, Percentage	25.00%

The percentage of the purchase price using cash on hand as the source of funding for a business acquisition.

No definition available.

Name:	hmsy_BusinessAcquisitionFundingSourceCashOnHandPercentage
Namespace Prefix:	hmsy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of the purchase price using an existing credit line as the source of funding for a business acquisition.

+ References

No definition available.

+ Details

Name:	hmsy_BusinessAcquisitionFundingSourceExistingCreditLinePercentage
Namespace Prefix:	hmsy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=hmsy_ElizaHoldingCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: