| Document | Oct. 22, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Oct. 22, 2019 |
| Entity Registrant Name | HEALTHCARE SERVICES GROUP INC |
| Entity File Number | 0-12015 |
| Entity Incorporation, State or Country Code | PA |
| Entity Tax Identification Number | 23-2018365 |
| Entity Address, Address Line One | 3220 Tillman Drive |
| Entity Address, Address Line Two | Suite 300 |
| Entity Address, City or Town | Bensalem |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19020 |
| City Area Code | 215 |
| Local Phone Number | 639-4274 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $.01 par value |
| Trading Symbol | HCSG |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000731012 |
