Information for United States Insurance Companies & Global Indemnity Reinsurance, Net of Intercompany Eliminations, as Determined in Accordance With SAP and Bermuda (Detail) - Global Indemnity Reinsurance - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statutory Accounting Practices [Line Items]
Statutory capital and surplus, as of end of period	$ 838,923	$ 713,842	$ 923,862
Statutory net income (loss)	$ 32,768	$ 864	$ 44,593