Reinsurance - Ceded Premiums Earned and Reinsurance Recoveries on Losses and Loss Adjustment Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Insurance [Abstract]
Ceded premiums earned	$ 450	$ 372	$ 265
Reinsurance recoveries on losses and loss adjustment expenses	$ 589	$ 239	$ 137