Schedule of Proceeds From Sales of Available for Sale Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities	$ 381,389	$ 647,404	$ 415,739
Equity securities	$ 111,156	39,723	$ 191,765
Preferred stock		$ 1,540