Investments - Major Categories of Investment Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Investment Income [Line Items]
Investment income	$ 5,123	$ 5,716	$ 6,599
Investment expenses	(489)	(576)	(619)
Fixed maturities, available-for-sale [Member]
Net Investment Income [Line Items]
Investment income	4,481	4,914	6,434
Mutual funds, available-for-sale [Member]
Net Investment Income [Line Items]
Investment income	832	766	613
Other investments [Member]
Net Investment Income [Line Items]
Investment income	85	399
Other [Member]
Net Investment Income [Line Items]
Investment income	$ 214	$ 213	$ 171