Interim Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Available-for-sale securities, amortized cost	$ 585,579	$ 654,348
Common stock, shares authorized	15,000,000	15,000,000
Common stock, shares issued	7,836,442	7,799,867
Common stock, shares outstanding	7,836,442	7,799,867
Common stock, shares held in Rabbi Trust	18,151	19,401