Shareholders' Equity - Additional Information (Detail) - USD ($)				3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 29, 2017	Nov. 07, 2016	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Ordinary shares, par value	$ 0.0001			$ 0.0001	$ 0.0001	$ 0.0001
Share Premium	$ 434,730,000			$ 434,730,000	$ 434,730,000	$ 430,283,000
Additional Paid-in Capital
Equity, Class of Treasury Stock [Line Items]
Reduction in treasury shares due to redomestication			$ 103,248,000			103,248,000
Treasury Shares
Equity, Class of Treasury Stock [Line Items]
Reduction in treasury shares due to redomestication						(103,248,000)
Fox Paine and Company
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares purchased		3,397,031
Stock repurchase program, value of shares purchased		$ 83,000,000
Stock repurchase program, per share purchased		$ 24.44
Quarterly Dividend
Equity, Class of Treasury Stock [Line Items]
Dividend declared, per share				$ 0.25
Annual Dividend
Equity, Class of Treasury Stock [Line Items]
Dividend declared, per share					$ 1.00
Redemption Agreement | Fox Paine and Company
Equity, Class of Treasury Stock [Line Items]
Ordinary shares agreed to redeem, shares							8,260,870
Additional Redemption Agreement | Fox Paine and Company
Equity, Class of Treasury Stock [Line Items]
Ordinary shares agreed to redeem, shares							3,397,031
Redemption agreement expiration date					Dec. 31, 2019
Ordinary shares agreed to redeem							$ 78,100,000
Ordinary shares agreed to redeem, percentage of annual increase							3.00%
Global Indemnity Limited
Equity, Class of Treasury Stock [Line Items]
Reduction in treasury shares due to redomestication	9,000,000
Stock Issued during Period			17,597,230
Distributable reserves	275,800,000			$ 275,800,000	$ 275,800,000
Share Premium	434,700,000			434,700,000	434,700,000
Global Indemnity Limited | Maximum
Equity, Class of Treasury Stock [Line Items]
Maximum dividends and distributions allowable under law	$ 719,600,000			$ 719,600,000	$ 719,600,000
Ordinary Shares A
Equity, Class of Treasury Stock [Line Items]
Ordinary shares, cancelled			13,463,864
Ordinary shares, par value			$ 0.0001
Reduction in treasury shares due to redomestication						$ 1,000
Ordinary Shares A | Treasury Shares
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares purchased					29,551	28,099	11,895
Stock repurchase program, value of shares purchased					$ 1,159,000	$ 805,000	$ 333,000
Ordinary Shares A | Global Indemnity Limited
Equity, Class of Treasury Stock [Line Items]
Ordinary shares, par value			$ 0.0001
Stock Issued during Period			13,463,864
Ordinary Shares B
Equity, Class of Treasury Stock [Line Items]
Ordinary shares, cancelled			4,133,366
Ordinary shares, par value			$ 0.0001
Ordinary shares agreed to redeem, shares	0			0	0	0
Ordinary Shares B | Global Indemnity Limited
Equity, Class of Treasury Stock [Line Items]
Ordinary shares, par value			$ 0.0001
Stock Issued during Period			4,133,366