Investments, Debt Securities, Amortized Cost and Fair Value by Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available-for-Sale Debt Securities, Amortized Cost [Abstract]
Due in one year or less	$ 17,816
Due after one year through five years	71,725
Due after five years through ten years	49,897
Due after ten years	111,117
Amortized cost	250,555	$ 237,807
Available-for-Sale Debt Securities, Fair Value [Abstract]
Due in one year or less	17,979
Due after one year through five years	75,025
Due after five years through ten years	51,081
Due after ten years	113,703
Fair value	$ 257,788	$ 240,706