Schedule of Condensed Consolidating Statements of Comprehensive Income (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net income (loss)		$ 6,721	$ 3,728	$ 40,984	$ 16,621
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses)		9,421	(1,624)	48,883	(22,632)
Equity in other comprehensive income (loss) of unconsolidated subsidiaries		0	0	0	0
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss)		(2)	7	(4)	(1)
Reclassification adjustment for gains included in net income		(847)	717	(2,665)	1,403
Unrealized foreign currency translation gains (losses)		200	(454)	331	(1,554)
Other comprehensive income (loss), net of tax		8,772	(1,354)	46,545	(22,784)
Comprehensive income (loss), net of tax		15,493	2,374	87,529	(6,163)
Global Indemnity Limited (Parent co-obligor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net income (loss)		6,721	3,728	40,984	16,621
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses)		0	(63)	880	(210)
Equity in other comprehensive income (loss) of unconsolidated subsidiaries		8,772	(1,392)	46,226	(22,695)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss)		0	0	0	0
Reclassification adjustment for gains included in net income		0	101	(561)	121
Unrealized foreign currency translation gains (losses)		0	0	0	0
Other comprehensive income (loss), net of tax		8,772	(1,354)	46,545	(22,784)
Comprehensive income (loss), net of tax		15,493	2,374	87,529	(6,163)
Global Indemnity Group, Inc.(Subsidiary co-obligor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net income (loss)		(4,462)	(8,434)	10,903	(21,335)
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses)		0	(845)	1,567	(2,930)
Equity in other comprehensive income (loss) of unconsolidated subsidiaries		4,711	(603)	24,201	(9,633)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss)		0	0	0	0
Reclassification adjustment for gains included in net income		(8)	659	235	1,048
Unrealized foreign currency translation gains (losses)		0	0	0	0
Other comprehensive income (loss), net of tax		4,703	(789)	26,003	(11,515)
Comprehensive income (loss), net of tax		241	(9,223)	36,906	(32,850)
Other Global Indemnity Limited Subsidiaries and Eliminations (non-co-obligor subsidiaries)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	[1]	9,726	2,687	60,654	45,816
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses)	[1]	9,421	(716)	46,436	(19,492)
Equity in other comprehensive income (loss) of unconsolidated subsidiaries	[1]	4,703	(789)	26,003	(11,515)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss)	[1]	(2)	7	(4)	(1)
Reclassification adjustment for gains included in net income	[1]	(839)	(43)	(2,339)	234
Unrealized foreign currency translation gains (losses)	[1]	200	(454)	331	(1,554)
Other comprehensive income (loss), net of tax	[1]	13,483	(1,995)	70,427	(32,328)
Comprehensive income (loss), net of tax	[1]	23,209	692	131,081	13,488
Consolidation Adjustments
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	[2]	(5,264)	5,747	(71,557)	(24,481)
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses)	[2]	0	0	0	0
Equity in other comprehensive income (loss) of unconsolidated subsidiaries	[2]	(18,186)	2,784	(96,430)	43,843
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss)	[2]	0	0	0	0
Reclassification adjustment for gains included in net income	[2]	0	0	0	0
Unrealized foreign currency translation gains (losses)	[2]	0	0	0	0
Other comprehensive income (loss), net of tax	[2]	(18,186)	2,784	(96,430)	43,843
Comprehensive income (loss), net of tax	[2]	$ (23,450)	$ 8,531	$ (167,987)	$ 19,362

[1] Includes all other subsidiaries of Global Indemnity Limited and eliminations

[2] Includes Parent co-obligor and subsidiary co-obligor consolidating adjustments