Investments by Category and Level (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities
Available-for-sale Securities	$ 943,623	$ 834,531
US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	98,975	92,626
Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	3,982	2,036
US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	144,468	201,512
Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	23,890	20,257
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	301,988	287,562
Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	223,854	143,265
Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	64,037	14,905
Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,151	692
Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	862,345	762,855
Mutual Fund
Schedule of Available-for-sale Securities
Available-for-sale Securities	50,016	31,924
Public Utility, Equities
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,759	1,702
Common Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	27,198	27,902
Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,005	1,767
Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	80,978	63,295
Other Long-term Investments
Schedule of Available-for-sale Securities
Available-for-sale Securities	300	8,381
Level 1
Schedule of Available-for-sale Securities
Available-for-sale Securities	79,275	64,287
Level 1 | US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	790	692
Level 1 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	790	692
Level 1 | Mutual Fund
Schedule of Available-for-sale Securities
Available-for-sale Securities	47,223	31,924
Level 1 | Public Utility, Equities
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,759	1,702
Level 1 | Common Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	27,198	27,902
Level 1 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,005	1,767
Level 1 | Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	78,185	63,295
Level 1 | Other Long-term Investments
Schedule of Available-for-sale Securities
Available-for-sale Securities	300	300
Level 2
Schedule of Available-for-sale Securities
Available-for-sale Securities	864,348	769,610
Level 2 | US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	98,975	92,626
Level 2 | Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	3,982	2,036
Level 2 | US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	144,468	201,512
Level 2 | Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	23,890	20,257
Level 2 | Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	301,988	287,562
Level 2 | Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	223,854	143,265
Level 2 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	64,037	14,905
Level 2 | Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	361	0
Level 2 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	861,555	762,163
Level 2 | Mutual Fund
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,793	0
Level 2 | Public Utility, Equities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 2 | Common Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 2 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 2 | Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,793	0
Level 2 | Other Long-term Investments
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	7,447
Level 3
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	634
Level 3 | US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Mutual Fund
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Public Utility, Equities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Common Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Other Long-term Investments
Schedule of Available-for-sale Securities
Available-for-sale Securities	$ 0	$ 634