Investments - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Unfunded commitments	$ 3,200,000
Amount contributed to funds	6,316,000
Fixed maturities and cash equivalents on deposit with various insurance departments at fair value and amortized cost	5,300,000
Cash equivalents on deposit with another insurance company at fair value and amortized cost	9,400,000
Third Fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Amount contributed to funds	4,000,000
Collateralized Mortgage Obligations [Member] | Non-Agency Backed - Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	1,000,000	1,000,000
Collateralized Mortgage Obligations [Member] | Non-Agency Backed - Commercial [Member]
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	$ 200,000	$ 200,000