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RETIREMENT FUND AND PROFIT SHARING PLAN (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items] |  |  |
Employer match of the first 1% of compensation contributed by participants | 100.00% |  |
Percentage of participant contribution under condition one | 1.00% |  |
Employer match of the next 5% compensation contributed by participants, percentage | 50.00% |  |
Percentage of employee deferrals under condition two | 5.00% |  |
UNITED STATES | Common Class A [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Shares owned by plan (in shares) | 67,891 |  |
UNITED STATES | Common Class B [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Shares owned by plan (in shares) | 144,276 |  |
HONG KONG |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Employer matching contribution, percentage | 7.00% |  |
HONG KONG | Minimum [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Employer matching contribution, percentage | 5.00% |  |
HONG KONG | Maximum [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Employee matching contribution per participant under prior plan | 5.00% |  |
Retirement Fund [Member] | HONG KONG |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Compensation expenses | $ 300 | $ 300 | $ 300
Retirement Fund [Member] | HONG KONG | Common Class A [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Shares owned by plan (in shares) | 3,323 |  |
Retirement Fund [Member] | HONG KONG | Common Class B [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Shares owned by plan (in shares) | 17,342 |  |
401K Plan [Member] | UNITED STATES |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Compensation expenses | $ 1,200 | 1,100 | 1,200
SERP [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension expense | $ 1,700 | 1,600 | 1,500
Normal retirement age | 65 years |  |
Number of years of service | 20 years |  |
Number of years of plan participation | 5 years |  |
Percentage of average base compensation payable as normal retirement benefit under the plan | 40.00% |  |
Early retirement age | 55 years |  |
Number of consecutive calendar years of plan participation to calculate average base compensation | 20 years |  |
Number of monthly payments under the death benefit of the plan | 120 months |  |
Period for which beneficiary is entitled to receive benefit | shorter of (i) the time necessary to complete 120 monthly payments or (ii) 60 months |  |
Percentage of participant's annual base salary received by beneficiary for one year from date of death | 100.00% |  |
Period for which beneficiary will receive hundred percent annual base salary | 1 year |  |
Percentage of participant's annual base salary received by beneficiary for years two through five following date of death | 50.00% |  |
Period for which beneficiary will receive fifty percent annual base salary | 4 years |  |
Components of SERP expense [Abstract] |  |  |
Service Cost | $ 700 | 593 | 552
Interest Cost | 673 | 659 | 567
Net amortization | 375 | 391 | 366
Net periodic benefit cost | 1,748 | 1,643 | 1,485
Summary of information about changes in plan assets, benefit obligation, and the funded status [Abstract] |  |  |
Fair value of plan assets, beginning of period | 0 | 0 |
Company contributions | 240 | 129 |
Benefits paid | (240) | (129) |
Fair value of plan assets, end of period | 0 | 0 | 0
Benefit obligation January 1 | 16,900 | 15,576 |
Service cost | 700 | 593 | 552
Interest cost | 673 | 659 | 567
Benefits paid | (240) | (129) |
Plan amendments | 198 | 487 |
Actuarial (gains) losses | 903 | (286) |
Benefit obligation, December 31 | 19,134 | 16,900 | $ 15,576
Underfunded status, December 31 | (19,134) | (16,900) |
Accumulated benefit obligation | 16,100 | 13,800 |
Fair value of life insurance policies and marketable securities held in a rabbi trust | 14,000 | 12,700 |
Estimated net loss and prior service cost that will be amortized from accumulated other comprehensive income into net periodic benefit cost over the next fiscal year | 400 |  |
Expected employer contributions in next fiscal year | 300 |  |
Expected future benefit payments [Abstract] |  |  |
2018 | 317 |  |
2019 | 564 |  |
2020 | 622 |  |
2021 | 622 |  |
2222 | 909 |  |
2023 - 2027 | 5,193 |  |
Amounts recognized in accumulated other comprehensive loss, pretax [Abstract] |  |  |
Prior service cost | 1,135 | 1,172 |
Net loss | 3,732 | 2,970 |
Total amounts recognized in accumulated other comprehensive loss | $ 4,867 | $ 4,142 |
Net periodic benefit cost [Abstract] |  |  |
Discount rate | 4.00% | 4.25% | 4.00%
Rate of compensation increase | 3.00% | 3.00% | 3.00%
Benefit obligation [Abstract] |  |  |
Discount rate | 3.50% | 4.00% | 4.25%
Rate of compensation increase | 3.00% | 3.00% | 3.00%
SERP [Member] | Minimum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Number of monthly payments entitled to beneficiary in case participant dies prior to receiving one hundred twenty monthly payments | 60 months |  |

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- Definition Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919 + Details
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