Investments by Category and Level (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities
Available-for-sale Securities	$ 1,001,970	$ 943,623
US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	120,816	98,975
Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	4,071	3,982
US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	133,751	144,468
Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	25,334	23,890
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	288,872	301,988
Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	251,903	223,854
Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	57,129	64,037
Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,985	1,151
Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	884,861	862,345
Mutual Fund
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	65,453	50,016
Public Utility, Equities
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	3,663	1,759
Common Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	44,492	27,198
Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	3,002	2,005
Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	116,610	80,978
Equity Securities, FV-NI	116,610	80,978
Other Long-term Investments
Schedule of Available-for-sale Securities
Available-for-sale Securities	499	300
Level 1
Schedule of Available-for-sale Securities
Available-for-sale Securities	117,657	79,275
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	747	790
Level 1 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	747	790
Level 1 | Mutual Fund
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	65,453	47,223
Level 1 | Public Utility, Equities
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	3,663	1,759
Level 1 | Common Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	44,492	27,198
Level 1 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	3,002	2,005
Level 1 | Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	116,610	78,185
Level 1 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	300	300
Level 2
Schedule of Available-for-sale Securities
Available-for-sale Securities	884,313	864,348
Level 2 | US Government and Government Agencies and Authorities
Schedule of Available-for-sale Securities
Available-for-sale Securities	120,816	98,975
Level 2 | Foreign Government Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	4,071	3,982
Level 2 | US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	133,751	144,468
Level 2 | Public Utility, Bonds
Schedule of Available-for-sale Securities
Available-for-sale Securities	25,334	23,890
Level 2 | Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	288,872	301,988
Level 2 | Mortgage Backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	251,903	223,854
Level 2 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	57,129	64,037
Level 2 | Redeemable Preferred Stock
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,238	361
Level 2 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	884,114	861,555
Level 2 | Mutual Fund
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	2,793
Level 2 | Public Utility, Equities
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	0
Level 2 | Common Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	0
Level 2 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	0
Level 2 | Equity Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	2,793
Level 2 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	199	0
Level 3
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
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
Equity Securities, FV-NI	0	0
Level 3 | Public Utility, Equities
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	0
Level 3 | Common Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	0	0
Level 3 | Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Equity Securities, FV-NI	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
Other Investments	$ 0	$ 0