Premises and Equipment (Schedule of Premises and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	$ 981,777	$ 944,353
Less accumulated depreciation and amortization	593,039	573,270
Net premises and equipment	388,738	371,083
Land [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	91,003	93,492
Building and improvements [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	622,642	582,056
Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	242,455	239,216
Right of use leased assets [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	$ 25,677	$ 29,589