Investment Securities - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Estimated Fair Values of Fixed-Maturity Securities (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	$ 82,409	$ 99,088
Total fixed-maturity securities, Gross Unrealized Gains	60	78
Total fixed-maturity securities, Gross Unrealized Losses	(10)	(111)
Total fixed-maturity securities, Estimated Fair Value	82,459	99,055
Unrestricted Fixed-Maturity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	52,959	66,481
Total fixed-maturity securities, Gross Unrealized Gains	7	14
Total fixed-maturity securities, Gross Unrealized Losses	(2)	(11)
Total fixed-maturity securities, Estimated Fair Value	52,964	66,484	[1]
Fixed-Maturity Securities Held in Trust [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	29,450	32,607
Total fixed-maturity securities, Gross Unrealized Gains	53	64
Total fixed-maturity securities, Gross Unrealized Losses	(8)	(100)
Total fixed-maturity securities, Estimated Fair Value	29,495	32,571	[1]
U.S. Government Treasury Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	249	249
Total fixed-maturity securities, Gross Unrealized Gains	1
Total fixed-maturity securities, Gross Unrealized Losses		(1)
Total fixed-maturity securities, Estimated Fair Value	250	248
Obligations of U.S. Government Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	61,435	69,392
Total fixed-maturity securities, Gross Unrealized Gains	8	13
Total fixed-maturity securities, Gross Unrealized Losses	(2)	(23)
Total fixed-maturity securities, Estimated Fair Value	61,441	69,382
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	12,907	21,048
Total fixed-maturity securities, Gross Unrealized Gains	44	62
Total fixed-maturity securities, Gross Unrealized Losses	(3)	(49)
Total fixed-maturity securities, Estimated Fair Value	12,948	21,061
Foreign Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	7,818	8,399
Total fixed-maturity securities, Gross Unrealized Gains	7	3
Total fixed-maturity securities, Gross Unrealized Losses	(5)	(38)
Total fixed-maturity securities, Estimated Fair Value	$ 7,820	$ 8,364

[1] Balances derived from audited financial statements as of December 31, 2015.