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Note 21 - Stockholders' Equity - Company's Significant Subsidiaries (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% |
Simmons First National Corporation [Member] |  |
Capital | $ 1,388,970 | $ 912,948
Capital to Risk Weighted Assets | 11.40% | 15.10%
Capital Required for Capital Adequacy | $ 974,716 | $ 483,681
Capital Required for Capital Adequacy to Risk Weighted Assets | 8.00% | 8.00%
Tier One Risk Based Capital | $ 1,199,457 | $ 872,707
Tier One Risk Based Capital to Risk Weighted Assets | 9.80% | 14.50%
Tier One Risk Based Capital Required for Capital Adequacy | $ 734,361 | $ 361,120
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 6.00% | 6.00%
Common Equity Tier 1 Capital | $ 1,199,457 | $ 812,310
Common Equity Tier 1 Capital to Average Assets | 9.80% | 13.50%
Common Equity Tier 1 Capital Required for Capital Adequacy | $ 550,771 | $ 270,770
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% | 4.50%
Tier One Leverage Capital | $ 1,199,457 | $ 872,707
Tier One Leverage Capital to Average Assets | 9.20% | 11.00%
Tier One Leverage Capital Required for Capital Adequacy | $ 521,503 | $ 317,348
Tier One Leverage Capital Required for Capital Adequacy to Average Assets | 4.00% | 4.00%
Simmons First National Bank [Member] |  |
Capital | $ 877,728 | $ 830,921
Capital to Risk Weighted Assets | 12.10% | 13.80%
Capital Required for Capital Adequacy | $ 580,316 | $ 481,693
Capital Required for Capital Adequacy to Risk Weighted Assets | 8.00% | 8.00%
Capital Required to be Well Capitalized | $ 725,395 | $ 602,117
Capital Required to be Well Capitalized to Risk Weighted Assets | 10.00% | 10.00%
Tier One Risk Based Capital | $ 835,787 | $ 790,673
Tier One Risk Based Capital to Risk Weighted Assets | 11.50% | 13.20%
Tier One Risk Based Capital Required for Capital Adequacy | $ 436,063 | $ 359,397
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 6.00% | 6.00%
Tier One Risk Based Capital Required to be Well Capitalized | $ 581,417 | $ 479,196
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets | 8.00% | 8.00%
Common Equity Tier 1 Capital | $ 835,787 | $ 790,673
Common Equity Tier 1 Capital to Average Assets | 11.50% | 13.20%
Common Equity Tier 1 Capital Required for Capital Adequacy | $ 327,047 | $ 269,548
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% | 4.50%
Common Equity Tier 1 Capital Required to Be Well Capitalized | $ 472,401 | $ 389,347
Common Equity Tier 1 Capital Required to Be Well Capitalized to Average Assets | 6.50% | 6.50%
Tier One Leverage Capital | $ 835,787 | $ 790,673
Tier One Leverage Capital to Average Assets | 9.20% | 10.00%
Tier One Leverage Capital Required for Capital Adequacy | $ 363,386 | $ 316,269
Tier One Leverage Capital Required for Capital Adequacy to Average Assets | 4.00% | 4.00%
Tier One Leverage Capital Required to be Well Capitalized | $ 454,232 | $ 395,337
Tier One Leverage Capital Required to be Well Capitalized to Average Assets | 5.00% | 5.00%
Bank SNB [Member] |  |
Capital | $ 259,077 |
Capital to Risk Weighted Assets | 10.90% |
Capital Required for Capital Adequacy | $ 190,148 |
Capital Required for Capital Adequacy to Risk Weighted Assets | 8.00% |
Capital Required to be Well Capitalized | $ 237,685 |
Capital Required to be Well Capitalized to Risk Weighted Assets | 10.00% |
Tier One Risk Based Capital | $ 255,360 |
Tier One Risk Based Capital to Risk Weighted Assets | 10.70% |
Tier One Risk Based Capital Required for Capital Adequacy | $ 143,193 |
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 6.00% |
Tier One Risk Based Capital Required to be Well Capitalized | $ 190,923 |
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets | 8.00% |
Common Equity Tier 1 Capital | $ 255,360 |
Common Equity Tier 1 Capital to Average Assets | 10.70% |
Common Equity Tier 1 Capital Required for Capital Adequacy | $ 107,394 |
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% |
Common Equity Tier 1 Capital Required to Be Well Capitalized | $ 155,125 |
Common Equity Tier 1 Capital Required to Be Well Capitalized to Average Assets | 6.50% |
Tier One Leverage Capital | $ 255,360 |
Tier One Leverage Capital to Average Assets | 10.10% |
Tier One Leverage Capital Required for Capital Adequacy | $ 101,133 |
Tier One Leverage Capital Required for Capital Adequacy to Average Assets | 4.00% |
Tier One Leverage Capital Required to be Well Capitalized | $ 126,416 |
Tier One Leverage Capital Required to be Well Capitalized to Average Assets | 5.00% |
Southwest Bank [Member] |  |
Capital | $ 297,164 |
Capital to Risk Weighted Assets | 11.00% |
Capital Required for Capital Adequacy | $ 216,119 |
Capital Required for Capital Adequacy to Risk Weighted Assets | 8.00% |
Capital Required to be Well Capitalized | $ 270,149 |
Capital Required to be Well Capitalized to Risk Weighted Assets | 10.00% |
Tier One Risk Based Capital | $ 294,874 |
Tier One Risk Based Capital to Risk Weighted Assets | 10.90% |
Tier One Risk Based Capital Required for Capital Adequacy | $ 162,316 |
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 6.00% |
Tier One Risk Based Capital Required to be Well Capitalized | $ 216,421 |
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets | 8.00% |
Common Equity Tier 1 Capital | $ 294,874 |
Common Equity Tier 1 Capital to Average Assets | 10.90% |
Common Equity Tier 1 Capital Required for Capital Adequacy | $ 121,737 |
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% |
Common Equity Tier 1 Capital Required to Be Well Capitalized | $ 175,842 |
Common Equity Tier 1 Capital Required to Be Well Capitalized to Average Assets | 6.50% |
Tier One Leverage Capital | $ 294,874 |
Tier One Leverage Capital to Average Assets | 12.20% |
Tier One Leverage Capital Required for Capital Adequacy | $ 96,680 |
Tier One Leverage Capital Required for Capital Adequacy to Average Assets | 4.00% |
Tier One Leverage Capital Required to be Well Capitalized | $ 120,850 |
Tier One Leverage Capital Required to be Well Capitalized to Average Assets | 5.00% |

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- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 + Details
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- Definition The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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- Definition Total Capital divided by risk weighted assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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- Definition Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as well-capitalized under regulatory framework for prompt corrective action. + References No definition available. + Details
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- Definition Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
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- Definition The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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- Definition The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
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- Definition The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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