Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Fair value of held-to-maturity investment securities	$ 45,639	$ 32
Accumulated amortization and fair value adjustments on other intangibles	$ 11,646	$ 9,495
Common stock, par value	$ 5	$ 5
Common stock, shares authorized	48,000,000	48,000,000
Common stock, shares issued	18,266,404	18,266,404
Common stock, shares outstanding	16,702,376	16,648,303
Treasury stock, shares	1,564,028	1,618,101