Note 20 - Stockholders' Equity (Details) - Company's Significant Subsidiaries (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Simmons First National Corporation [Member]
Total Risk-Based Capital Ratio
Capital	$ 435,185	$ 380,347
Capital to Risk Weighted Assets	14.50%	14.10%
Capital Required for Capital Adequacy	240,102	215,800
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required To Be Well Capitalized
Tier 1 Risk-Based Capital Ratio
Tier One Risk Based Capital	403,110	351,334
Tier One Risk Based Capital to Risk Weighted Assets	13.40%	13.00%
Tier One Risk Based Capital Required for Capital Adequacy	120,331	108,103
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to Be Well Capitalized
Tier 1 Leverage Ratio
Tier One Leverage Capital	403,110	351,334
Tier One Leverage Capital to Average Assets	8.80%	9.20%
Tier One Leverage Capital Required for Capital Adequacy	183,232	152,754
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to Be Well Capitalized
Simmons First National Bank [Member]
Total Risk-Based Capital Ratio
Capital	432,590	275,961
Capital to Risk Weighted Assets	14.50%	14.80%
Capital Required for Capital Adequacy	238,670	149,168
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required To Be Well Capitalized	298,338	186,460
Capital Required To Be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier 1 Risk-Based Capital Ratio
Tier One Risk Based Capital	405,834	261,318
Tier One Risk Based Capital to Risk Weighted Assets	13.60%	14.00%
Tier One Risk Based Capital Required for Capital Adequacy	119,363	74,662
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to Be Well Capitalized	179,044	111,993
Tier One Risk Based Capital Required to Be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Tier 1 Leverage Ratio
Tier One Leverage Capital	405,834	261,318
Tier One Leverage Capital to Average Assets	8.90%	10.10%
Tier One Leverage Capital Required for Capital Adequacy	182,397	103,492
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to Be Well Capitalized	$ 227,997	$ 129,365
Tier One Leverage Capital Required to Be Well Capitalized to Average Assets	5.00%	5.00%

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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Tier 1 Risk Based Capital as defined in the regulations.

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