Loans - Schedule of Loans in Deferral (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	$ 74,062	$ 702,650	$ 1,077,043
Construction and land development
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	1,032	9,359	14,488
Commercial real estate - owner occupied
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	14,248	204,710	320,406
Commercial real estate - non-owner occupied
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	32,549	344,573	445,311
Residential real estate
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	12,839	75,885	148,035
Commercial and financial
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	11,915	61,308	130,877
Consumer
Financing Receivable, Nonaccrual [Line Items]
Value of loans deferred, not classified as TDRs, excluding PPP loans	$ 1,479	$ 6,815	$ 17,926