Investments (Details 2) $ in Thousands	Jun. 30, 2018 USD ($)
Amortized cost
Due in one year or less	$ 94,467
Due after one year through five years	241,546
Due after five years through ten years	249,068
Due after ten years	123,814
Amortized cost, fixed maturities	708,895
Estimated fair value
Due in one year or less	94,408
Due after one year through five years	242,016
Due after five years through ten years	246,058
Due after ten years	122,946
Estimated fair value, fixed maturities	$ 705,428