Acquisition of Frederick County Bancorp, Inc. - Fair Value Adjustments (Details)	Jan. 11, 2020 USD ($)
Business Acquisition [Line Items]
Gross amortized cost basis at January 11, 2020	$ 339,577,000
Interest rate fair value adjustment on pools of homogeneous loans	2,600,000
Credit fair value adjustment on pools of homogeneous loans	5,300,000
Frederick County Bancorp, Inc.
Business Acquisition [Line Items]
Gross amortized cost basis at January 11, 2020	339,577,000
Interest rate fair value adjustment on pools of homogeneous loans	(2,632,000)
Credit fair value adjustment on pools of homogeneous loans	(5,326,000)
Fair value of acquired loans at January 11, 2020	329,917,000
Purchased credit impaired loans | Frederick County Bancorp, Inc.
Business Acquisition [Line Items]
Credit fair value adjustment on pools of homogeneous loans	$ (1,702,000)