v3.19.3
Cover Page - shares
9 Months Ended
Sep. 30, 2019
Oct. 31, 2019
Document Information [Line Items]    
Document Type 10-Q  
Entity Interactive Data Current Yes  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Entity Registrant Name DONEGAL GROUP INC  
Entity Central Index Key 0000800457  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Shell Company false  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Address, State or Province PA  
Class A Common Stock [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   23,106,528
Title of 12(b) Security Common Stock  
Trading Symbol DGICA  
Security Exchange Name NASDAQ  
Class B Common Stock [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   5,576,775
Title of 12(b) Security Common Stock  
Trading Symbol DGICB  
Security Exchange Name NASDAQ