Note 21 - Condensed Financial Information (Parent Company Only) (Details) - Condensed Balance Sheets (Parentheticals) (Parent Company [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Unrealized appreciation on available-for-sale securities, income taxes	$ (862)	$ (1,938)

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:	debit
Period Type:	instant