Cover Page - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 19, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	0-12015
Entity Registrant Name	HEALTHCARE SERVICES GROUP, INC.
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
Title of 12(b) Security	Common Stock ($.01 par value)
Security Exchange Name	NASDAQ
Trading Symbol	HCSG
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 1,430
Entity Common Stock, Shares Outstanding		74,404
Documents Incorporated by Reference	Portions of the definitive Proxy Statement for the Registrant’s Annual Meeting of Shareholders to be held on May 26, 2020 have been incorporated by reference into Parts II and III of this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Central Index Key	0000731012
Current Fiscal Year End Date	--12-31