Premises and Equipment, Summary Composition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 641,701
Accumulated Depreciation	311,386
Net Book Value	330,315	$ 267,606
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	57,471
Accumulated Depreciation	0
Net Book Value	57,471	52,104
Land improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	12,572
Accumulated Depreciation	5,929
Net Book Value	$ 6,643	6,661
Land improvements | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	15 years
Land improvements | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	3 years
Buildings
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 332,256
Accumulated Depreciation	130,104
Net Book Value	$ 202,152	141,432
Buildings | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	39 years
Buildings | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	5 years
Computers
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 42,190
Accumulated Depreciation	33,139
Net Book Value	$ 9,051	6,372
Computers | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	5 years
Computers | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	3 years
Furniture, fixtures and other equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 162,253
Accumulated Depreciation	119,704
Net Book Value	$ 42,549	49,794
Furniture, fixtures and other equipment | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	15 years
Furniture, fixtures and other equipment | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	3 years
Leasehold improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 34,959
Accumulated Depreciation	22,510
Net Book Value	$ 12,449	$ 11,243
Leasehold improvements | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	15 years
Leasehold improvements | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	3 years