Investments (Details 2) $ in Thousands	Sep. 30, 2018 USD ($)
Amortized cost
Due in one year or less	$ 105,133
Due after one year through five years	230,247
Due after five years through ten years	247,101
Due after ten years	125,801
Amortized cost, fixed maturities	708,282
Estimated fair value
Due in one year or less	105,031
Due after one year through five years	230,234
Due after five years through ten years	244,336
Due after ten years	124,594
Estimated fair value, fixed maturities	$ 704,195