Summary of Business Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015		Dec. 31, 2015
Revenues:
Gross premiums written		$ 154,319		$ 166,515		$ 295,685		$ 309,384
Net premiums written		125,310		146,005		242,182		272,109
Net premiums earned		117,804		128,877		239,440		256,214
Other income (loss)		795		577		1,751		1,129
Total revenues		118,599		129,454		241,191		257,343
Losses and Expenses:
Net losses and loss adjustment expenses		78,111		79,560		142,895		149,179
Acquisition costs and other underwriting expenses		48,542		50,926		100,632		99,184
Income (loss) from segments		(8,054)		(1,032)		(2,336)		8,980
Unallocated Items:
Net investment income		6,562		9,141		16,308		17,382
Net realized investment gains (losses)		(3,492)		6,532		(10,985)		3,562
Corporate and other operating expenses		(4,255)		(4,334)		(8,058)		(15,874)
Interest expense		(2,229)		(535)		(4,444)		(1,040)
Income (loss) before income taxes		(11,468)		9,772		(9,515)		13,010
Income tax benefit		6,303		1,345		11,475		4,901
Net income (loss)		(5,165)		11,117		1,960		17,911
Total assets		2,006,094		2,260,458		2,006,094		2,260,458		$ 1,957,294
Reinsurance Operations
Revenues:
Gross premiums written	[1]	12,408		18,478		25,143		38,343
Net premiums written	[1]	12,394		18,478		25,129		38,304
Net premiums earned	[1]	8,888		13,345		21,105		26,546
Other income (loss)	[1]	(66)		13		28		(66)
Total revenues	[1]	8,822		13,358		21,133		26,480
Losses and Expenses:
Net losses and loss adjustment expenses	[1]	3,712		4,341		8,317		8,439
Acquisition costs and other underwriting expenses	[1]	3,475		4,853		7,958		9,742
Income (loss) from segments	[1]	1,635		4,164		4,858		8,299
Unallocated Items:
Total assets	[1],[2]	712,291		761,412		712,291		761,412
Commercial Lines
Revenues:
Gross premiums written	[3]	58,030		59,033		107,121		108,826
Net premiums written	[3]	52,452		54,700		96,010		100,322
Net premiums earned	[3]	48,187		49,614		95,520		100,328
Other income (loss)	[3]	160		153		323		318
Total revenues	[3]	48,347		49,767		95,843		100,646
Losses and Expenses:
Net losses and loss adjustment expenses	[3]	29,712		30,039		54,718		59,642
Acquisition costs and other underwriting expenses	[3]	18,919	[4]	20,008	[5]	39,390	[6]	40,631	[7]
Income (loss) from segments	[3]	(284)		(280)		1,735		373
Unallocated Items:
Total assets	[3]	771,330		944,744		771,330		944,744
Personal Lines
Revenues:
Gross premiums written	[3]	83,881		89,004		163,421		162,215
Net premiums written	[3]	60,464		72,827		121,043		133,483
Net premiums earned	[3]	60,729		65,918		122,815		129,340
Other income (loss)	[3]	701		411		1,400		877
Total revenues	[3]	61,430		66,329		124,215		130,217
Losses and Expenses:
Net losses and loss adjustment expenses	[3]	44,687		45,180		79,860		81,098
Acquisition costs and other underwriting expenses	[3]	26,148	[8]	26,065	[9]	53,284	[10]	48,811	[11]
Income (loss) from segments	[3]	(9,405)		(4,916)		(8,929)		308
Unallocated Items:
Total assets	[3]	$ 522,473		$ 554,302		$ 522,473		$ 554,302

[1] External business only, excluding business assumed from affiliates.

[2] Comprised of Global Indemnity Reinsurance's total assets less its investment in subsidiaries.

[3] Includes business ceded to the Company's Reinsurance Operations.

[4] Includes federal excise tax of $132 relating to cessions from Commercial Lines to Reinsurance Operations.

[5] Includes federal excise tax of $261 relating to cessions from Commercial Lines to Reinsurance Operations.

[6] Includes federal excise tax of $259 relating to cessions from Commercial Lines to Reinsurance Operations.

[7] Includes federal excise tax of $529 relating to cessions from Commercial Lines to Reinsurance Operations.

[8] Includes federal excise tax of $303 relating to cessions from Personal Lines to Reinsurance Operations.

[9] Includes federal excise tax of $330 relating to cessions from Personal Lines to Reinsurance Operations.

[10] Includes federal excise tax of $614 relating to cessions from Personal Lines to Reinsurance Operations.

[11] Includes federal excise tax of $647 relating to cessions from Personal Lines to Reinsurance Operations.