Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Available-for-sale securities, amortized cost	$ 654,348	$ 561,893
Common stock, shares authorized	15,000,000	15,000,000
Common stock, shares issued	7,799,867	7,776,274
Common stock, shares outstanding	7,799,867	7,776,274