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Note 9 - Stock-based Compensation (Details) - Share-based Compensation Activity (USD $) | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2014 | Dec. 31, 2013 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009 | Jun. 30, 2014 Restricted Stock [Member] Mercantile Plans [Member] | Dec. 31, 2013 Restricted Stock [Member] Mercantile Plans [Member] | Dec. 31, 2012 Restricted Stock [Member] Mercantile Plans [Member] | Jun. 30, 2014 Restricted Stock [Member] | Dec. 31, 2013 Restricted Stock [Member] | Dec. 31, 2011 Restricted Stock [Member] | Dec. 31, 2010 Restricted Stock [Member] | Dec. 31, 2009 Restricted Stock [Member] | Jun. 30, 2014 Mercantile Plans [Member] | Dec. 31, 2013 Mercantile Plans [Member] | Dec. 31, 2012 Mercantile Plans [Member]
Note 9 - Stock-based Compensation (Details) - Share-based Compensation Activity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Nonvested, shares |  |  |  |  |  | 63,800 | 66,100 | 38,650 |  |  |  |  |  |  |  |
Nonvested, weighted average fair value |  |  |  |  |  | $ 14.30 | $ 14.30 | $ 6.20 |  |  |  |  |  |  |  |
Outstanding, shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 60,876 | 152,896 | 214,903
Outstanding, weighted average exercise price |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 33.11 | $ 26.15 | $ 22.40
Options exercisable at period-end |  |  |  |  |  |  |  |  |  |  |  |  |  | 56,890 | 60,876 | 152,896
Options exercisable at period-end |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 33.79 | $ 33.11 | $ 26.15
Granted | 0 | 0 | 0 | 0 | 0 |  |  |  |  |  |  |  |  | 0 | 0 | 0
Granted |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercised |  |  |  |  |  |  |  |  |  |  |  |  |  | (2,845) | (51,055) | (50,930)
Exercised |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 17.74 | $ 13.72 | $ 10.83
Forfeited or expired |  |  |  |  |  |  |  |  |  |  |  |  |  | (1,141) | (40,965) | (11,077)
Forfeited or expired |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 37.55 | $ 31.30 | $ 23.77
Granted |  |  |  |  |  | 0 | 0 | 66,100 | 0 | 0 | 0 | 0 | 0 |  |  |
Granted |  |  |  |  |  |  |  | $ 14.30 |  |  |  |  |  |  |  |
Vested |  |  |  |  |  | (63,300) | 0 | (38,266) |  |  |  |  |  |  |  |
Vested |  |  |  |  |  | $ 14.30 |  | $ 6.20 |  |  |  |  |  |  |  |
Forfeited |  |  |  |  |  | (500) | (2,300) | (384) |  |  |  |  |  |  |  |
Forfeited |  |  |  |  |  | $ 14.30 | $ 14.30 | $ 6.20 |  |  |  |  |  |  |  |
Nonvested, shares |  |  |  |  |  | 0 | 63,800 | 66,100 |  |  |  |  |  |  |  |
Nonvested, weighted average fair value |  |  |  |  |  |  | $ 14.30 | $ 14.30 |  |  |  |  |  |  |  |
Outstanding, shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 56,890 | 60,876 | 152,896
Outstanding, weighted average exercise price |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 33.79 | $ 33.11 | $ 26.15

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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3)-(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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