Premises and Equipment, Summary Composition (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 694,050
Accumulated Depreciation	330,824
Net Book Value	363,225	$ 330,963
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	67,737
Accumulated Depreciation	0
Net Book Value	67,737	59,257
Land improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	14,730
Accumulated Depreciation	7,518
Net Book Value	$ 7,212	6,313
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 and improvements
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 363,000
Accumulated Depreciation	150,464
Net Book Value	$ 212,536	198,431
Buildings and improvements \| Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	39 years
Buildings and improvements \| Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated Useful Lives	5 years
Computers
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 45,768
Accumulated Depreciation	33,375
Net Book Value	$ 12,392	11,078
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	$ 168,567
Accumulated Depreciation	118,676
Net Book Value	$ 49,891	42,049
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	$ 34,248
Accumulated Depreciation	20,791
Net Book Value	$ 13,457	$ 13,835
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

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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