XML 31 R1.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Feb. 28, 2020
Jun. 28, 2019
Document And Entity Information      
Entity Registrant Name STERLING CONSTRUCTION CO INC    
Entity Central Index Key 0000874238    
Current Fiscal Year End Date --12-31    
Entity Filer Category Accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer No    
Entity Shell Company false    
Entity Emerging Growth Company false    
Entity Small Business false    
Entity Common Stock, Shares Outstanding (in shares)   27,787,903  
Entity Public Float     $ 349.1
Document Type 10-K    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Amendment Flag false