XML 16 R1.htm IDEA: XBRL DOCUMENT v3.21.1
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Mar. 26, 2021
Jun. 30, 2020
Document Information [Line Items]      
Entity Central Index Key 0001494582    
Entity Registrant Name BOSTON OMAHA Corp    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2020    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Document Transition Report false    
Entity File Number 001-38113    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 27-0788438    
Entity Address, Address Line One 1601 Dodge Street, Suite 3300    
Entity Address, City or Town Omaha    
Entity Address, State or Province NE    
Entity Address, Postal Zip Code 68102    
City Area Code 857    
Local Phone Number 256-0079    
Title of 12(b) Security Class A common stock, $0.001 par value per share    
Trading Symbol BOMN    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 237,457,984
Common Class B [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   1,055,560  
Common Class A [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   26,175,555