Loans and Allowance for Credit Losses - Nonaccrual and Past Due Greater than 90 Days (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	$ 72,135	$ 73,836
Financing Receivable, Nonaccrual, No Allowance	36,817	36,537
Financing Receivable, 90 Days or More Past Due, Still Accruing	2,833	2,362
Commercial real estate - Owner occupied
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	13,023	10,231
Financing Receivable, Nonaccrual, No Allowance	8,955	5,985
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	3,459	5,219
Financing Receivable, Nonaccrual, No Allowance	0	1,522
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer real estate – mortgage
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	19,779	22,191
Financing Receivable, Nonaccrual, No Allowance	0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	273
Construction and land development
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	1,558	1,953
Financing Receivable, Nonaccrual, No Allowance	0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	34,288	34,238
Financing Receivable, Nonaccrual, No Allowance	27,862	29,030
Financing Receivable, 90 Days or More Past Due, Still Accruing	2,491	1,785
Consumer and other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual loans	28	4
Financing Receivable, Nonaccrual, No Allowance	0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	$ 342	$ 304