Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Securities available for sale, amortized cost	$ 813,049	$ 673,315
Securities held to maturity	$ 38,293	$ 42,695
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,867,630	50,867,630
Common stock, shares in treasury	437,363	591,057