SCHEDULE I -- SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		$ 600,504	$ 521,017
Investments classified as cash and cash equivalents		156,855
Total Investments [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		667,606
Fair value		666,739
Amount at which shown in the balance sheet	[1]	666,739
Bonds [Member] | Total Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		600,504
Fair value		592,645
Amount at which shown in the balance sheet	[1]	592,645
Bonds [Member] | Agency Collateralized Mortgage Obligations [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		10,636
Fair value		10,687
Amount at which shown in the balance sheet	[1]	10,687
Bonds [Member] | Agency Mortgage-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		37,168
Fair value		37,385
Amount at which shown in the balance sheet	[1]	37,385
Bonds [Member] | Asset-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		66,241
Fair value		64,422
Amount at which shown in the balance sheet	[1]	64,422
Bonds [Member] | Bank Loans [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		10,208
Fair value		9,750
Amount at which shown in the balance sheet	[1]	9,750
Bonds [Member] | Certificates of Deposit [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		2,835
Fair value		2,835
Amount at which shown in the balance sheet	[1]	2,835
Bonds [Member] | Collateralized Mortgage Obligations [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		5,095
Fair value		5,423
Amount at which shown in the balance sheet	[1]	5,423
Bonds [Member] | Corporate Securities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		196,925
Fair value		190,450
Amount at which shown in the balance sheet	[1]	190,450
Bonds [Member] | Mortgage-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		38,586
Fair value		38,540
Amount at which shown in the balance sheet	[1]	38,540
Bonds [Member] | Municipal Obligations [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		29,102
Fair value		29,155
Amount at which shown in the balance sheet	[1]	29,155
Bonds [Member] | Non-U.S. Government Obligations [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		25,339
Fair value		25,180
Amount at which shown in the balance sheet	[1]	25,180
Bonds [Member] | U.S. Government Obligations [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		178,369
Fair value		178,818
Amount at which shown in the balance sheet	[1]	178,818
Common Stocks [Member] | Total Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		59,430
Fair value		66,422
Amount at which shown in the balance sheet	[1]	66,422
Common Stocks [Member] | Consumer [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		15,963
Fair value		17,945
Amount at which shown in the balance sheet	[1]	17,945
Common Stocks [Member] | Energy [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		3,981
Fair value		3,179
Amount at which shown in the balance sheet	[1]	3,179
Common Stocks [Member] | Financial [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		23,111
Fair value		25,253
Amount at which shown in the balance sheet	[1]	25,253
Common Stocks [Member] | Industrial [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		3,287
Fair value		6,920
Amount at which shown in the balance sheet	[1]	6,920
Common Stocks [Member] | Technology [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		1,259
Fair value		2,303
Amount at which shown in the balance sheet	[1]	2,303
Common Stocks [Member] | Funds (e.g. mutual funds, closed end funds, ETFs) [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		6,797
Fair value		5,489
Amount at which shown in the balance sheet	[1]	5,489
Common Stocks [Member] | Other [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		5,032
Fair value		5,333
Amount at which shown in the balance sheet	[1]	5,333
Commercial Mortgage Loans [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		6,672
Fair value		6,672
Amount at which shown in the balance sheet		6,672
Short-term [Member] | Total Short-term and Other [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		1,000
Fair value		1,000
Amount at which shown in the balance sheet	[1]	1,000
Short-term [Member] | Certificates of Deposit [Member]
Summary of Investments, Other than Investments in Related Parties [Abstract]
Cost		1,000
Fair value		1,000
Amount at which shown in the balance sheet	[1]	$ 1,000

[1] Amounts presented above do not include investments of $156,855 classified as cash and cash equivalents in the consolidated balance sheet.