Premises and Equipment - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross rental expense	$ 4.9	$ 4.7
Gross rental expense, before adoption of 842			$ 4.7
Minimum
Property, Plant and Equipment [Line Items]
Operating lease renewal term	5 years
Maximum
Property, Plant and Equipment [Line Items]
Operating lease renewal term	20 years