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NET INCOME PER COMMON SHARE AND EQUITY PER COMMON SHARE (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Shares used in computing basic and diluted net income per share [Abstract] |  |  |
Weighted average common shares outstanding during the period for Basic computation (in shares) | 9,098,000 | 8,960,000 | 8,884,000
Dilutive effect of employee stock options (in shares) | 63,000 | 45,000 | 42,000
Weighted average common shares outstanding during the period for Diluted computation (in shares) | 9,161,000 | 9,005,000 | 8,926,000
Common stock excluded from calculations of diluted net income per share (in shares) | 0 | 0 | 67,500
Class of Stock [Line Items] |  |  |
Equity per common share (in dollars per share) | $ 15.28 | $ 14.77 | $ 14.14
Common Stock [Member] | Class A Stock [Member] |  |  |
Class of Stock [Line Items] |  |  |
Common stock, shares authorized (in shares) | 15,000,000 | 15,000,000 | 15,000,000
Common stock, shares issued (in shares) | 8,246,033 | 8,176,213 | 8,030,677
Common stock, shares outstanding (in shares) | 8,246,033 | 8,176,213 | 8,030,677
Common stock, par value (in dollars per share) | $ 1.00 |  |
Common stock, shares issued during period (in shares) | 69,820 | 145,536 | 82,108
Common Stock [Member] | Class B Stock [Member] |  |  |
Class of Stock [Line Items] |  |  |
Common stock, shares authorized (in shares) | 1,040,000 | 1,040,000 | 1,040,000
Common stock, shares issued (in shares) | 881,452 | 881,452 | 881,452
Common stock, shares outstanding (in shares) | 881,452 | 881,452 | 881,452
Common stock, par value (in dollars per share) | $ 1.00 |  |

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- Definition Total number of common shares of an entity that have been sold or granted to shareholders (excludes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding. + References No definition available. + Details
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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Antidilution -URI http://asc.fasb.org/extlink&oid=6505113 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Diluted Earnings Per Share -URI http://asc.fasb.org/extlink&oid=6510752 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Contingent Stock Agreement -URI http://asc.fasb.org/extlink&oid=6508534 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 + Details
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- Definition The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. + References No definition available. + Details
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- Definition The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=64863997&loc=d3e1505-109256 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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