Deferred Policy Acquisition costs - Schedule of the Activity in the Deferred Policy Acquisition Costs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Movement Analysis Of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of year	$ 18,419	$ 16,578	$ 15,137
Policy acquisition costs deferred	41,278	40,961	36,064
Amortization expense during the year	(40,526)	(39,120)	(34,623)
Balance, end of year	$ 19,171	$ 18,419	$ 16,578