Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Debt securities, available-for-sale, cost (in dollars)	$ 403,554	$ 397,800
Equity securities, available for sale, cost (in dollars)	$ 33,187	$ 31,502
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	1,609,374	1,609,374