Investments (Details 2) $ in Thousands	Jun. 30, 2017 USD ($)
Amortized cost
Due in one year or less	$ 71,180
Due after one year through five years	330,763
Due after five years through ten years	223,344
Due after ten years	110,706
Amortized cost, fixed maturities	735,993
Estimated fair value
Due in one year or less	71,283
Due after one year through five years	334,532
Due after five years through ten years	227,888
Due after ten years	110,979
Estimated fair value, fixed maturities	$ 744,682