Investment Securities - Schedule of Investments in Accordance with Fair Value Measurement (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	$ 76,831	$ 99,055
Total investments fair value	81,379	106,356
Money Market Funds [Member]
Class of securities:
Money market funds	4,548	7,301
U.S. Government Treasury Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	249	248
Obligations of U.S. Government Sponsored Enterprises [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	59,371	69,382
Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	11,415	21,061
Foreign Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	5,796	8,364
Level 1
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	60,567	75,037
Total investments fair value	65,115	82,338
Level 1 | Money Market Funds [Member]
Class of securities:
Money market funds	4,548	7,301
Level 1 | U.S. Government Treasury Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	249	248
Level 1 | Obligations of U.S. Government Sponsored Enterprises [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	47,489	63,909
Level 1 | Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	7,033	8,873
Level 1 | Foreign Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	5,796	2,007
Level 2
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	16,264	24,018
Total investments fair value	16,264	24,018
Level 2 | Obligations of U.S. Government Sponsored Enterprises [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	11,882	5,473
Level 2 | Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	$ 4,382	12,188
Level 2 | Foreign Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value		$ 6,357