Description of Business and Significant Accounting Policies - Concentrations of Credit Risk and Significant Clients (Details) - financial_institution	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Number of financial institutions holding cash and cash equivalents and marketable securities	1	1
Percentage of revenue from major customer	17.60%

Concentration Risk, Number of Financial Institutions Holding Cash and Cash Equivalents and Marketable Securities

No definition available.

Name:	hcsg_ConcentrationRiskNumberofFinancialInstitutionsHoldingCashandCashEquivalentsandMarketableSecurities
Namespace Prefix:	hcsg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant