Summary of Significant Accounting Policies - Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	37 years 6 months
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	50 years
Furniture, fixtures, and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Furniture, fixtures, and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	10 years
Software
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Automobiles
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years