Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Consolidated Balance Sheets [Abstract]
Debt securities, available-for-sale, cost (in dollars)	$ 570,080	$ 538,629
Equity securities, available for sale, cost (in dollars)	$ 27,460	$ 24,951
Common stock, par value (in dollars per share)	$ 0.18	$ 0.18
Common stock, authorized shares	33,333,333	33,333,333
Common stock, issued shares	20,872,831	20,872,831
Treasury stock, shares	1,893,291	1,775,512