Investment Securities - Schedule of Investments in Accordance with Fair Value Measurement (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	$ 106,005	$ 60,641
Total investments fair value	122,281	149,492
Money Market Funds [Member]
Class of securities:
Money market funds	16,276	88,851
Level 1
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	82,355	20,770
Total investments fair value	98,631	109,621
Level 1 | Money Market Funds [Member]
Class of securities:
Money market funds	16,276	88,851
Level 2
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	23,650	39,871
Total investments fair value	23,650	39,871
Obligations of U.S. Government Sponsored Enterprises [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	74,380	6,475
Obligations of U.S. Government Sponsored Enterprises [Member] | Level 1
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	69,887	3,009
Obligations of U.S. Government Sponsored Enterprises [Member] | Level 2
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	4,493	3,466
Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	21,589	41,484
Corporate Debt Securities [Member] | Level 1
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	11,396	14,939
Corporate Debt Securities [Member] | Level 2
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	10,193	26,545
Foreign Corporate Debt Securities [Member]
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	10,036	12,682
Foreign Corporate Debt Securities [Member] | Level 1
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	1,072	2,822
Foreign Corporate Debt Securities [Member] | Level 2
Class of securities:
Total fixed-maturity securities, Estimated Fair Value	$ 8,964	$ 9,860