Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Commitment and Contingencies
Accrued litigation or other legal proceedings expenses	$ 2.3

Represents the amount of accrued litigation or other legal proceedings expenses.

No definition available.

Name:	hmsy_AccruedLitigationOrOtherLegalProceedingsExpenses
Namespace Prefix:	hmsy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration