Note 8 - Income Taxes (Details) - Tax Effects of Temporary Differences Related to Deferred Taxes Included in Other Liabilities: (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Loans acquired	$ 31,413sfnc_DeferredTaxAssetsLoansAcquired	$ 16,925sfnc_DeferredTaxAssetsLoansAcquired
FDIC true-up liability	2,797sfnc_DeferredTaxAssetsFdicTrueUpLiab	2,792sfnc_DeferredTaxAssetsFdicTrueUpLiab
Allowance for loan losses	11,444	11,749
Valuation of foreclosed assets	15,420sfnc_DeberredTaxAssetsonForclosedAssets	14,167sfnc_DeberredTaxAssetsonForclosedAssets
Tax NOLs from acquisition	11,819	11,819
Deferred compensation payable	2,533	1,536
Vacation compensation	1,630	1,456
Accumulated depreciation		1,937
Loan interest	2,099sfnc_DeferredTaxAssetsLoanInterest	1,693sfnc_DeferredTaxAssetsLoanInterest
Accrued pension and profit sharing	1,793	1,793
Accrued equity and other compensation	4,814	3,356
Acquired securities	2,083	2,568
Accrued merger related costs	2,730	2,464
Basis difference in partnership investments	812	617
Unrealized loss on available-for-sale securities		862
Other	3,173us-gaap_DeferredTaxAssetsOther	1,666us-gaap_DeferredTaxAssetsOther
Gross deferred tax assets	94,560us-gaap_DeferredTaxAssetsGross	77,400us-gaap_DeferredTaxAssetsGross
Deferred tax liabilities:
Goodwill and other intangible amortization	(25,780)	(16,953)
FDIC acquired assets	(1,754)	(4,377)
Deferred loan fee income and expenses, net	(1,663)	(1,515)
FHLB stock dividends	(2,227)	(1,160)
Limitations under IRC Sec 382	(10,839)	(11,169)
Prepayment liabilities	(1,979)	(1,141)
Accumulated depreciation	(402)
Unrealized gain on available-for-sale securities	(1,197)
Other	(545)us-gaap_DeferredTaxLiabilitiesOther	(337)us-gaap_DeferredTaxLiabilitiesOther
Gross deferred tax liabilities	(46,386)us-gaap_DeferredTaxLiabilities	(36,652)us-gaap_DeferredTaxLiabilities
Net deferred tax asset, included in other assets	$ 48,174us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 40,748us-gaap_DeferredTaxAssetsLiabilitiesNet

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