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Document and Entity Information (USD $)	9 Months Ended
Document and Entity Information (USD $)	Sep. 30, 2011	Sep. 30, 2010	Oct. 31, 2011 Class A Shares	Oct. 31, 2011 Class B Shares
Entity Registrant Name	DONEGAL GROUP INC
Entity Central Index Key	0000800457
Document Type	10-Q
Document Period End Date	Sep. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$ 157,257,918
Entity Common Stock, Shares Outstanding			19,975,609	5,576,775