Loans and Allowance - Summary of allowance for credit losses (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Troubled debt restructured loans	$ 40,000	$ 41,000
Non-accrual and 90+ days past due and still accruing loans to average loans	1.46%	1.45%
Allowance for credit losses to non-accrual and 90 days or more and still accruing loans	46.70%	49.80%
Consumer
Financing Receivable, Impaired [Line Items]
Troubled debt restructured loans	$ 40,000