Investments Equity Investments, by Category (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Mutual Fund
Schedule of Available-for-sale Securities
Fair Value	$ 50,016	$ 31,924
Percent of Total	61.80%	50.40%
Public Utility, Equities
Schedule of Available-for-sale Securities
Fair Value	$ 1,759	$ 1,702
Percent of Total	2.20%	2.70%
Common Stock
Schedule of Available-for-sale Securities
Fair Value	$ 27,198	$ 27,902
Percent of Total	33.60%	44.10%
Nonredeemable Preferred Stock
Schedule of Available-for-sale Securities
Fair Value	$ 2,005	$ 1,767
Percent of Total	2.40%	2.80%
Equity Securities
Schedule of Available-for-sale Securities
Fair Value	$ 80,978	$ 63,295
Percent of Total	100.00%	100.00%