Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 31, 2020
Document Information [Line Items]
Document Type	10-Q
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Document Quarterly Report	true
Document Transition Report	false
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
Entity Address, Address Line One	1195 River Road, P.O. Box 302
Entity Address, City or Town	Marietta
Entity Address, Postal Zip Code	17547
Entity File Number	0-15341
Entity Tax Identification Number	23-2424711
City Area Code	717
Local Phone Number	426-1931
Entity Incorporation, State or Country Code	DE
Class A Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		24,195,190
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