Loans Acquired - Impact of the Adjustments on the Company's Financial Results for the Following Reporting Periods (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Receivables [Abstract]
Impact on net interest income and pre-tax income	$ 26	$ 1,388	$ 476	$ 2,572
Impact, net of taxes	$ 19	$ 844	$ 350	$ 1,563

The amount of increase/decrease in net after-tax income for the current year due to the accretable yield adjustment.

No definition available.

Name:	sfnc_CertainLoansAcquiredInTransferAccretableYieldAdjPeriodIncreaseDecreaseNet
Namespace Prefix:	sfnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration