CONDENSED CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Investments held-to-maturity, fair value	$ 223,130	$ 216,007
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	25,076,794	24,990,021
Common stock, shares outstanding	25,076,794	24,990,021