Consolidated Statements Of Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Held-to-maturity securities	$ 787,489	$ 607,602	$ 1,010,179
Preferred stock, no par value (usd per share)
Preferred stock, shares authorized	20,000,000	20,000,000	20,000,000
Common stock, no par value (usd per share)
Common stock, $1.00 stated value (usd per share)	$ 1.00	$ 1.00	$ 1.00
Common stock, 100,000,000 shares authorized	100,000,000	100,000,000	100,000,000
Common stock, shares issued	55,801,665	51,978,289	51,708,585
Treasury stock, shares	101,738	97,749	89,430
Series C Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 1,000	$ 1,000	$ 1,000
Preferred stock, shares outstanding	0	126,257	126,257
Series D Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25	$ 25	$ 25
Preferred stock, shares outstanding	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	5,000,000	5,000,000	5,000,000