XML 15 R1.htm IDEA: XBRL DOCUMENT v3.21.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Mar. 28, 2021
Jun. 30, 2020
Document and Entity Information      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2020    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Entity Registrant Name CLEARSIGN TECHNOLOGIES CORP    
Entity Central Index Key 0001434524    
Current Fiscal Year End Date --12-31    
Title of 12(b) Security Common Stock    
Trading Symbol CLIR    
Security Exchange Name NASDAQ    
Entity Small Business true    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Public Float     $ 44,000,000
Entity Common Stock, Shares Outstanding   30,900,634  
Entity Emerging Growth Company false    
Entity Shell Company false