Investments (Details 2) $ in Thousands	Dec. 31, 2016 USD ($)
Amortized cost
Due in one year or less	$ 55,304
Due after one year through five years	329,377
Due after five years through ten years	203,880
Due after ten years	113,842
Amortized cost, fixed maturities	702,403
Estimated fair value
Due in one year or less	55,394
Due after one year through five years	331,617
Due after five years through ten years	207,358
Due after ten years	112,972
Estimated fair value, fixed maturities	$ 707,341