Investments - Schedule of Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	$ 1,091,008	$ 1,001,970
U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	123,130	120,816
Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,869	4,071
States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	162,681	133,751
Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	41,955	25,334
Corporate Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	347,666	288,872
Mortgage-backed securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	279,417	251,903
Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	63,351	57,129
Redeemable Preferred Stocks
Schedule of Available-for-sale Securities
Available-for-sale Securities	6,369	2,985
Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,026,438	884,861
Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value		3,663
Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	20,343	44,492
Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	8,182	3,002
Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	36,470	116,610
Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	28,100	499
Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	7,945	65,453
Level 1
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	38,357	117,657
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	1,587	747
Level 1 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,587	747
Level 1 | Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value		3,663
Level 1 | Common Stock
Schedule of Available-for-sale Securities
Equity securities, fair value	20,343	44,492
Level 1 | Nonredeemable Preferred Stocks
Schedule of Available-for-sale Securities
Equity securities, fair value	8,182	3,002
Level 1 | Equity Securities
Schedule of Available-for-sale Securities
Equity securities, fair value	36,470	116,610
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	7,945	65,453
Level 2
Schedule of Available-for-sale Securities
Investment Owned, at Fair Value	1,052,651	884,313
Level 2 | U.S. Government and Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	123,130	120,816
Level 2 | Foreign Government
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,869	4,071
Level 2 | States, Municipalities and Political Subdivisions
Schedule of Available-for-sale Securities
Available-for-sale Securities	162,681	133,751
Level 2 | Public Utilities
Schedule of Available-for-sale Securities
Available-for-sale Securities	41,955	25,334
Level 2 | Corporate Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	347,666	288,872
Level 2 | Mortgage-backed securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	279,417	251,903
Level 2 | Asset-backed Securities
Schedule of Available-for-sale Securities
Available-for-sale Securities	63,351	57,129
Level 2 | Redeemable Preferred Stocks
Schedule of Available-for-sale Securities
Available-for-sale Securities	4,782	2,238
Level 2 | Fixed Maturities
Schedule of Available-for-sale Securities
Available-for-sale Securities	1,024,851	884,114
Level 2 | Public Utilities
Schedule of Available-for-sale Securities
Equity securities, fair value		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	0	0
Level 2 | Other Long-term Investments
Schedule of Available-for-sale Securities
Other Investments	27,800	199
Level 2 | Mutual Fund
Schedule of Available-for-sale Securities
Equity securities, fair value	0	0
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
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