Premiums Receivable - Components of Premiums Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Premiums Receivable, Net [Abstract]
Premiums receivable	$ 188,217	$ 190,216
Allowance for doubtful accounts	(5,212)	(4,852)	$ (5,211)	$ (5,458)
Premiums receivable, net	$ 183,005	$ 185,364