Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Commitments to extend credit	$ 384,411
Standby letters of credit	$ 11,727

Contractual amount for all off-balance sheet commitments.

No definition available.

Name:	smbk_OutstandingOffBalanceSheetRisksAmountLiability
Namespace Prefix:	smbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant