Loans and Allowance for Credit Losses - Loan Modifications not Classified as TDRs (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) contract	Dec. 31, 2020 USD ($) contract
Receivables [Abstract]
Portfolio loans: Interest Only | $	$ 49,888	$ 43,379
Portfolio loans: Full Payment Deferral | $	7,533	22,165
Portfolio loans: Total | $	$ 57,421	$ 65,544
Number of modifications: Interest Only | contract	21,000	23,000
Number of modifications: Full Payment Deferral | contract	3,000	11,000
Number of modifications: Total | contract	24,000	34,000