Investment Securities - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Estimated Fair Values of Fixed-Maturity Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	$ 76,912	$ 99,088
Total fixed-maturity securities, Gross Unrealized Gains	15	78
Total fixed-maturity securities, Gross Unrealized Losses	(96)	(111)
Total fixed-maturity securities, Estimated Fair Value	76,831	99,055
Unrestricted Fixed-Maturity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	47,635	66,481
Total fixed-maturity securities, Gross Unrealized Gains		14
Total fixed-maturity securities, Gross Unrealized Losses	(10)	(11)
Total fixed-maturity securities, Estimated Fair Value	47,625	66,484
Fixed-Maturity Securities Held in Trust [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	29,277	32,607
Total fixed-maturity securities, Gross Unrealized Gains	15	64
Total fixed-maturity securities, Gross Unrealized Losses	(86)	(100)
Total fixed-maturity securities, Estimated Fair Value	29,206	32,571
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 Losses		(1)
Total fixed-maturity securities, Estimated Fair Value	249	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	59,450	69,392
Total fixed-maturity securities, Gross Unrealized Gains	1	13
Total fixed-maturity securities, Gross Unrealized Losses	(80)	(23)
Total fixed-maturity securities, Estimated Fair Value	59,371	69,382
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	11,415	21,048
Total fixed-maturity securities, Gross Unrealized Gains	9	62
Total fixed-maturity securities, Gross Unrealized Losses	(9)	(49)
Total fixed-maturity securities, Estimated Fair Value	11,415	21,061
Foreign Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	5,798	8,399
Total fixed-maturity securities, Gross Unrealized Gains	5	3
Total fixed-maturity securities, Gross Unrealized Losses	(7)	(38)
Total fixed-maturity securities, Estimated Fair Value	$ 5,796	$ 8,364