Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for uncollectable reinsurance
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 11,332	$ 11,332	$ 11,520
Charged (Credited) to Costs and Expenses	(4,411)		(188)
Charged to Other Accounts	0	0	0
Deductions (Describe)	0	0	0
Ending Balance	6,921	11,332	11,332
Valuation allowance in deferred taxes
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	776	554	499
Charged (Credited) to Costs and Expenses	(55)	222	55
Charged to Other Accounts	0	0	0
Deductions (Describe)	0	0	0
Ending Balance	$ 721	$ 776	$ 554