Summary of Activity in Reserve for Losses and LAE (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Insurance [Abstract]
Net reserves for losses and LAE at beginning of year	$ 1,308,136	$ 1,222,633	$ 1,216,909
Provision for losses and LAE for claims occurring in the current year	637,267	601,041	520,227
Increase (decrease) in estimated losses and LAE for claims occurring in prior years	(64,669)	(55,812)	(1,266)
Incurred losses and LAE	572,598	545,229	518,961
Losses and LAE paid for claims occurring during:
Current year	(159,802)	(158,806)	(147,864)
Prior years	(320,863)	(295,527)	(365,479)
Losses and LAE payments	(480,665)	(454,333)	(513,343)
Foreign Currency Adjustment	(6,943)	(5,393)	106
Net reserves for losses and LAE at end of year	1,393,126	1,308,136	1,222,633
Reinsurance recoverables on unpaid losses and LAE	809,518	851,498	822,438
Gross reserves for losses and LAE at end of year	$ 2,202,644	$ 2,159,634	$ 2,045,071