Estimated Earned Premium and Incurred Losses (Detail) - Hiscox Bermuda - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Related Party Transaction [Line Items]
Assumed earned premium	$ 47	$ 1,823	$ 2,294	$ 4,639
Assumed losses and loss adjustment expenses	$ (167)	$ 504	$ 476	$ 1,349