Loans and Allowance for Credit Losses - Rollforward of Purchase Credit Impaired Loans (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Gross Carrying Value
Gross carrying value, beginning balance	$ 29,544
Reclassification of discount to allowance for credit losses	0
Year-to-date settlements	5,600
Gross carrying value, ending balance	23,944
Accretable Yield
Accretable yield, beginning balance	(4,801)
Reclassification of discount to allowance for credit losses	0
Year-to-date settlements	2,240
Accretable yield, ending balance	(2,561)
Nonaccretable Yield
Nonaccretable yield, beginning balance	(3,828)
Reclassification of discount to allowance for credit losses	3,828
Year-to-date settlements	0
Nonaccretable yield, ending balance	0
Net Carrying Value
Net carrying value, beginning balance	20,915
Reclassification of discount to allowance for credit losses	3,828
Year-to-date settlements	3,360
Net carrying value, ending balance	$ 21,383