Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 02, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
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 Incorporation, State or Country Code	DE
Entity Address, State or Province	PA
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 208,752,753
Class A Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		23,277,039
Title of 12(b) Security	Class A 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	Class B Common Stock
Trading Symbol	DGICB
Security Exchange Name	NASDAQ