Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2019
Mar. 30, 2020
Jun. 30, 2019
Document and Entity Information [Abstract]      
Entity Registrant Name KBL MERGER CORP. IV    
Entity Central Index Key 0001690080    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Type 10-K    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Filer Category Non-accelerated Filer    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Small Business true    
Entity File Number 001-38105    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Entity Shell Company true    
Entity Public Float     $ 50,158,786
Entity Common Stock, Shares Outstanding   4,491,767  
Entity Incorporation State Country Code DE