Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Securities Held-to-Maturity, Fair Value	$ 55,320	$ 24,871
Accumulated amortization and fair value adjustments on other intangibles	$ 21,825	$ 17,597
Common stock, par value	$ 5	$ 5
Common stock, shares authorized	48,000,000	48,000,000
Common stock, shares issued	31,556,799	28,911,799
Common stock, shares outstanding	29,334,859	26,589,353
Treasury stock, shares	2,221,940	2,322,446