Schedule of Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net cash provided by (used for) operating activities		$ 32,376	$ 42,069	$ (18,909)
Cash flows from investing activities:
Proceeds from sale of fixed maturities		977,321	293,348	918,439
Proceeds from sale of equity securities		260,891	35,639	32,218
Proceeds from maturity of fixed maturities		180,546	55,182	145,475
Proceeds from other invested assets		16,757	43,377	12,299
Amount received (paid) in connection with derivatives		(7,654)	4,392	1,464
Purchases of fixed maturities		(1,129,567)	(370,536)	(1,078,199)
Purchases of equity securities		(365,255)	(36,258)	(36,647)
Purchases of other invested assets		(13,283)	(16,309)	(24,000)
Acquisition of business		0	(3,515)	0
Net cash provided by (used for) investing activities		(80,244)	5,320	(28,951)
Cash flows from financing activities:
Net borrowings (repayments) under margin borrowing facility		7,811	(6,412)	5,584
Redemption of ordinary shares		0	0	(83,015)
Proceeds from issuance of subordinated notes		0	0	130,000
Debt issuance cost		0	0	(4,246)
Dividends paid to shareholders		(14,222)	(14,027)	0
Capital contribution		0		0
Purchase of A ordinary shares		(947)	(1,867)	(1,159)
Net cash provided by (used for) financing activities		(7,358)	(22,306)	47,164
Proceeds / (issuance) of notes to affiliates			0	0
Debt restructuring			0
Dividends from subsidiaries			0	0
Net change in cash and cash equivalents		(55,226)	25,083	(696)
Cash and cash equivalents at beginning of period		99,497	74,414	75,110
Cash and cash equivalents at end of period		44,271	99,497	74,414
Global Indemnity Limited (Parent co-obligor) | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used for) operating activities		2,632	(20,178)	(24,927)
Cash flows from investing activities:
Proceeds from sale of fixed maturities		48,393	32,980	12,389
Proceeds from sale of equity securities		10,900	0	0
Proceeds from maturity of fixed maturities		0	5,431	10,000
Proceeds from other invested assets		4,363	1,500	0
Amount received (paid) in connection with derivatives		0	0	0
Purchases of fixed maturities		(10,548)	(33,327)	(32,044)
Purchases of equity securities		(41,815)	0	0
Purchases of other invested assets		0	0	0
Acquisition of business			0
Net cash provided by (used for) investing activities		11,293	6,584	(9,655)
Cash flows from financing activities:
Net borrowings (repayments) under margin borrowing facility		0	0	0
Redemption of ordinary shares				(83,015)
Proceeds from issuance of subordinated notes				130,000
Debt issuance cost				(4,246)
Dividends paid to shareholders		(14,222)	(14,027)
Capital contribution		0		(96,000)
Purchase of A ordinary shares		(947)	(1,867)	(1,159)
Net cash provided by (used for) financing activities		(15,169)	4,726	45,580
Proceeds / (issuance) of notes to affiliates			230,000	0
Debt restructuring			(230,000)
Dividends from subsidiaries			20,620	100,000
Net change in cash and cash equivalents		(1,244)	(8,868)	10,998
Cash and cash equivalents at beginning of period		2,221	11,089	91
Cash and cash equivalents at end of period		977	2,221	11,089
Global Indemnity Group, LLC (Subsidiary co-obligor) | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used for) operating activities		(23,295)	(35,207)	(37,165)
Cash flows from investing activities:
Proceeds from sale of fixed maturities		101,584	71,900	54,082
Proceeds from sale of equity securities		249,991	35,639	32,218
Proceeds from maturity of fixed maturities		0	7,600	78,925
Proceeds from other invested assets		12,394	34,499	4,139
Amount received (paid) in connection with derivatives		(7,654)	4,392	1,464
Purchases of fixed maturities		(26,205)	(40,858)	(254,152)
Purchases of equity securities		(311,711)	(36,258)	(36,647)
Purchases of other invested assets		(13,283)	(15,800)	(22,500)
Acquisition of business			(3,515)
Net cash provided by (used for) investing activities		5,116	57,599	(142,471)
Cash flows from financing activities:
Net borrowings (repayments) under margin borrowing facility		7,811	(6,412)	5,584
Redemption of ordinary shares				0
Proceeds from issuance of subordinated notes				0
Debt issuance cost				0
Dividends paid to shareholders		0	0
Capital contribution		(13,008)		0
Purchase of A ordinary shares		0	0	0
Net cash provided by (used for) financing activities		(5,197)	(4,102)	181,849
Proceeds / (issuance) of notes to affiliates			(227,690)	120,000
Debt restructuring			230,000
Dividends from subsidiaries			0	56,265
Net change in cash and cash equivalents		(23,376)	18,290	2,213
Cash and cash equivalents at beginning of period		26,039	7,749	5,536
Cash and cash equivalents at end of period		2,663	26,039	7,749
Other Global Indemnity Limited Subsidiaries and Eliminations (non-co-obligor subsidiaries)
Cash flows from operating activities:
Net cash provided by (used for) operating activities	[1]	53,039	97,454	43,183
Cash flows from investing activities:
Proceeds from sale of fixed maturities	[1]	827,344	188,468	851,968
Proceeds from sale of equity securities	[1]	0	0	0
Proceeds from maturity of fixed maturities	[1]	180,546	42,151	56,550
Proceeds from other invested assets	[1]	0	7,378	8,160
Amount received (paid) in connection with derivatives	[1]	0	0	0
Purchases of fixed maturities	[1]	(1,092,814)	(296,351)	(792,003)
Purchases of equity securities	[1]	(11,729)	0	0
Purchases of other invested assets	[1]	0	(509)	(1,500)
Acquisition of business	[1]		0
Net cash provided by (used for) investing activities	[1]	(96,653)	(58,863)	123,175
Cash flows from financing activities:
Net borrowings (repayments) under margin borrowing facility	[1]	0	0	0
Redemption of ordinary shares	[1]			0
Proceeds from issuance of subordinated notes	[1]			0
Debt issuance cost	[1]			0
Dividends paid to shareholders	[1]	0	0
Capital contribution	[1]	13,008		96,000
Purchase of A ordinary shares	[1]	0	0	0
Net cash provided by (used for) financing activities	[1]	13,008	(22,930)	(180,265)
Proceeds / (issuance) of notes to affiliates	[1]		(2,310)	(120,000)
Debt restructuring	[1]		0
Dividends from subsidiaries	[1]		(20,620)	(156,265)
Net change in cash and cash equivalents	[1]	(30,606)	15,661	(13,907)
Cash and cash equivalents at beginning of period	[1]	71,237	55,576	69,483
Cash and cash equivalents at end of period	[1]	$ 40,631	$ 71,237	$ 55,576

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