Investments - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) Security Fund	Dec. 31, 2015 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Number of securities | Security	0	4
Fair value	$ 0	$ 7,689,000
Gross unrealized losses	0	(241,000)
OTTI charges recognized in net income	$ 147,000
Number of investment funds | Fund	2
Unfunded commitments	$ 200,000
Fixed maturities and cash equivalents on deposit with various insurance departments at fair value and amortized cost	6,600,000
Cash equivalents on deposit with another insurance company at fair value and amortized cost	15,600,000
Collateralized mortgage obligations: Non-agency backed - residential
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	900,000	900,000
Collateralized mortgage obligations: Non-agency backed - commercial
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	$ 200,000	$ 200,000