Note 22 - Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Parent Company [Member]
Unrealized depreciation on available-for-sale securities, net of income taxes	$ (6,108)	$ (9,818)

Amount of income tax related to the accumulated appreciation or loss in value of the total of available-for-sale securities at the end of an accounting period.

No definition available.

Name:	sfnc_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax
Namespace Prefix:	sfnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant