Fair Value Measurements - Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Fixed maturity securities	$ 134,711	$ 136,536
Equity Securities	9,425	9,687
Short-term investments	2,505	11,427
Total marketable investments measured at fair value	142,543	153,590
Total investments measured at NAV	4,098	4,060
Total assets measured at fair value	146,641	157,650
Liabilities:
Total Liabilities measured at fair value	29,804	29,888
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Short-term investments	2,505	8,429
Total marketable investments measured at fair value	7,587	13,810
Liabilities:
Total Liabilities measured at fair value	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Short-term investments	0	2,998
Total marketable investments measured at fair value	134,956	139,780
Liabilities:
Total Liabilities measured at fair value		0
Significant Unobservable Inputs (Level 3)
Assets:
Short-term investments	0	0
Total marketable investments measured at fair value		0
Liabilities:
Total Liabilities measured at fair value	29,804	29,888
Partnership Interest [Member]
Assets:
Total investments measured at NAV	4,098	4,060
U.S. Government
Assets:
Fixed maturity securities	15,678	17,090
U.S. Government | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
U.S. Government | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	15,678	17,090
U.S. Government | Significant Unobservable Inputs (Level 3)
Assets:
Fixed maturity securities	0	0
State and local government
Assets:
Fixed maturity securities	16,552	17,503
State and local government | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
State and local government | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	16,552	17,503
State and local government | Significant Unobservable Inputs (Level 3)
Assets:
Fixed maturity securities	0	0
Corporate debt
Assets:
Fixed maturity securities	38,247	38,908
Corporate debt | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Corporate debt | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	38,247	38,908
Corporate debt | Significant Unobservable Inputs (Level 3)
Assets:
Fixed maturity securities	0	0
Asset-backed securities
Assets:
Fixed maturity securities	25,258	23,540
Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	25,258	23,540
Mortgage-backed securities
Assets:
Fixed maturity securities	32,761	33,458
Mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	32,761	33,458
Commercial mortgage-backed securities
Assets:
Fixed maturity securities	3,850	3,491
Commercial mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Commercial mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	3,850	3,491
Collateralized mortgage obligations
Assets:
Fixed maturity securities	2,365	2,546
Collateralized mortgage obligations | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	2,365	2,546
Debt securities
Assets:
Fixed maturity securities	134,711	136,536
Debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Fixed maturity securities	0	0
Debt securities | Significant Other Observable Inputs (Level 2)
Assets:
Fixed maturity securities	134,711	136,536
Debt securities | Significant Unobservable Inputs (Level 3)
Assets:
Fixed maturity securities		0
No Par, Common Stock
Assets:
Equity Securities	5,327	5,627
No Par, Common Stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Equity Securities	5,082	5,381
No Par, Common Stock | Significant Other Observable Inputs (Level 2)
Assets:
Equity Securities	245	246
No Par, Common Stock | Significant Unobservable Inputs (Level 3)
Assets:
Equity Securities	0	0
Senior Debt Obligations [Member]
Liabilities:
Debt	29,804	29,888
Senior Debt Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Debt	0	0
Senior Debt Obligations [Member] | Significant Other Observable Inputs (Level 2)
Liabilities:
Debt		0
Senior Debt Obligations [Member] | Significant Unobservable Inputs (Level 3)
Liabilities:
Debt	$ 29,804	$ 29,888