Summary of Significant Accounting Policies - Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Equipment, Furniture And Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Equipment, Furniture And Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Premises [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Premises [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	50 years
Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years