Cover - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 06, 2020	Jun. 28, 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	001-31932
Entity Registrant Name	CATASYS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	88-0464853
Entity Address, Address Line One	2120 Colorado Ave.
Entity Address, Address Line Two	Suite 230
Entity Address, City or Town	Santa Monica
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90404
City Area Code	310
Local Phone Number	444-4300
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CATS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 140,851,867
Entity Common Stock, Shares Outstanding		16,726,964
Documents Incorporated by Reference	Portions of the 2020 definitive Proxy Statement are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0001136174
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false