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Summary of Significant Accounting Policies (Summary of Useful Lives of Property, Plant and Equipment) (Details)
12 Months Ended
Dec. 31, 2020
Building [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, useful life 40 years
Leasehold improvements [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, estimated useful life Shorter of useful life or term of lease
Minimum [Member] | Building improvements [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, useful life 7 years
Minimum [Member] | Furniture, fixtures and equipment [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, useful life 3 years
Maximum [Member] | Building improvements [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, useful life 40 years
Maximum [Member] | Furniture, fixtures and equipment [Member]  
Property, Plant and Equipment [Line Items]  
Premises and equipment, useful life 5 years