Reinsurance - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2016 USD ($)
Ceded Credit Risk [Line Items]
Percentage of share in results of pooled business subsidiary	80.00%
Percentage of share in results of pooled business owned by third party	20.00%
Loss reinsurance, set retention amount	$ 1,000,000
Percentage of accumulation of losses	100.00%
Catastrophe reinsurance, set retention amount	$ 5,000,000
Catastrophe reinsurance, deductible amount	1,000,000
Donegal Mutual [Member]
Ceded Credit Risk [Line Items]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	$ 170,000,000