Loans and Allowance for Credit Losses - Nonaccrual and Past Due Greater than 90 Days (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	$ 71,390	$ 61,605
Financing Receivable, Nonaccrual, No Allowance	14,816
Financing Receivable, 90 Days or More Past Due, Still Accruing	1,313	1,615
Commercial real estate- owner occupied
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	10,625	11,654
Financing Receivable, Nonaccrual, No Allowance	5,704
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Commercial real estate- Non-owner occupied
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	6,010	7,173
Financing Receivable, Nonaccrual, No Allowance	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer real estate – mortgage
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	21,895	24,667
Financing Receivable, Nonaccrual, No Allowance	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	281	168
Construction and land development
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	3,152	2,278
Financing Receivable, Nonaccrual, No Allowance	1,152
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	28,948	15,685
Financing Receivable, Nonaccrual, No Allowance	7,960
Financing Receivable, 90 Days or More Past Due, Still Accruing	563	946
Consumer and other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	760	148
Financing Receivable, Nonaccrual, No Allowance	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	$ 469	$ 501