v3.19.3

Organization - Additional Information (Detail)		1 Months Ended	9 Months Ended	12 Months Ended	74 Months Ended
	Mar. 08, 2019 USD ($)	Jan. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Sep. 30, 2019 shares	Jul. 18, 2013 shares
Business Acquisition [Line Items]
Operations commenced date			Aug. 26, 1986
Stock ownership percentage owned by third party			51.80%
Number of operating segments | Segment			3
Voting power percentage of outstanding common stock			72.00%
Restructuring charge for employee termination costs			$ 1,900,000
Restructuring charges paid for employee termination costs			195,000	$ 1,500,000
Accrual of restructuring charge			$ 195,000
Atlantic States [Member]
Business Acquisition [Line Items]
Percentage of share in results of pooled business subsidiary			80.00%
Donegal Mutual [Member]
Business Acquisition [Line Items]
Percentage of share in results of pooled business owned by third party			20.00%
DFSC and North West [Member]
Business Acquisition [Line Items]
Consideration from sale of business	$ 20,500,000
Consideration from sale of business fair value at closing date	20,900,000
DFSC and North West [Member] | Donegal Mutual Insurance Company [Member]
Business Acquisition [Line Items]
Consideration from sale of business	85,800,000
Proceeds from dividend	$ 29,200,000
Peninsula [Member]
Business Acquisition [Line Items]
Expected proceeds from sale of real estate		$ 1,200,000
Impairment charge related to real estate transaction				1,100,000
Fair value of real asset held for sale				$ 1,200,000
Donegal Financial Services Corporation [Member]
Business Acquisition [Line Items]
Outstanding stock ownership percentage			48.20%		48.20%
Gain (Loss) on Sale of Equity Investments			$ 12,700,000
Donegal Financial Services Corporation [Member] | DFSC and North West [Member]
Business Acquisition [Line Items]
Outstanding stock ownership percentage	48.20%
Dividend payment to be received	$ 14,100,000
Class A Common Stock [Member]
Business Acquisition [Line Items]
Stock ownership percentage held by major shareholder			43.00%
Class A Common Stock [Member] | Stock Repurchase Program Two [Member]
Business Acquisition [Line Items]
Authority to purchase shares | shares						500,000
Common stock shares purchased | shares					57,658
Class B Common Stock [Member]
Business Acquisition [Line Items]
Stock ownership percentage held by major shareholder			84.00%

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