Defined Contribution Plan, Days of Service Needed to Enroll in Plan

No definition available.

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Namespace Prefix:	hmsy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_RetirementPlanNameAxis=hmsy_The401KPlanMember
Namespace Prefix:
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- Details

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Period Type:

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan Disclosure [Line Items]
Days of service needed in order to enroll in 401(k) plan	90 days
Maximum percentage for contribution	60.00%
Defined contribution plan, cost	$ 7.7	$ 7.3	$ 5.9
Amount Contributed on Percentage of Pay, Tier One \| The 401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Percent of match	100.00%
Percent of employee's gross pay matched	4.00%
Amount Contributed on Percentage of Pay, Tier Two \| The 401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Percent of match	50.00%
Percent of employee's gross pay matched	1.00%