Investments - Schedule of Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities
Equity securities, fair value	$ 104,629	$ 80,978
Investment Owned, at Fair Value	1,026,604	943,623
U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	115,413	98,975
Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	4,072	3,982
States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	137,447	144,468
Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	30,128	23,890
Corporate Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	296,493	301,988
Mortgage-backed securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	275,254	223,854
Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	60,287	64,037
Redeemable Preferred Stocks
Schedule of Available-for-sale Securities
Available-for-sale Securities	2,118	1,151
Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	921,212	862,345
Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value	2,917	1,759
Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	39,774	27,198
Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	1,801	2,005
Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	104,629	80,978
Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	763	300
Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	60,137	50,016
Level 1
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	102,116	79,275
Level 1 | U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 1 | Corporate 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 Stocks
Schedule of Available-for-sale Securities
Available-for-sale Securities	594	790
Level 1 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	594	790
Level 1 | Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value	2,917	1,759
Level 1 | Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	39,774	27,198
Level 1 | Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	1,801	2,005
Level 1 | Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	101,222	78,185
Level 1 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	300	300
Level 1 | Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	56,730	47,223
Level 2
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	924,488	864,348
Level 2 | U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	115,413	98,975
Level 2 | Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	4,072	3,982
Level 2 | States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	137,447	144,468
Level 2 | Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	30,128	23,890
Level 2 | Corporate Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	296,493	301,988
Level 2 | Mortgage-backed securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	275,254	223,854
Level 2 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	60,287	64,037
Level 2 | Redeemable Preferred Stocks
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,524	361
Level 2 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	920,618	861,555
Level 2 | Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 2 | Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 2 | Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 2 | Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	3,407	2,793
Level 2 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	463	0
Level 2 | Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	3,407	2,793
Level 3
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	0	0
Level 3 | U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	0	0
Level 3 | Corporate 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 Stocks
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 | Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 3 | Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 3 | Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 3 | Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
Level 3 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	0	0
Level 3 | Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	$ 0	$ 0