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COMMON STOCK (Details) $ / shares in Units, $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($) Shareholder $ / shares | Dec. 31, 2016 USD ($) $ / shares | Dec. 31, 2015 USD ($) $ / shares
Class of Stock [Line Items] |  |  |
Number of days from trigger date to purchase Class B common shares | 90 days |  |
Percentage of common stock held by shareholder one | 23.20% |  |
Common stock dividends declared | $ | $ 3.3 | $ 3.2 | $ 3.2
Minimum [Member] |  |  |
Class of Stock [Line Items] |  |  |
Percentage of outstanding common stock held by two shareholders | 10.00% |  |
Percentage of common stock needs to held by shareholders having more than ten percent of Class A common stock as per class B Protection clause | 10.00% |  |
Maximum [Member] |  |  |
Class of Stock [Line Items] |  |  |
Percentage shareholding of class B considered as per class B Protection clause | 10.00% |  |
Class A [Member] |  |  |
Class of Stock [Line Items] |  |  |
Number of shareholders with ownership in excess of ten percent | Shareholder | 1 |  |
Common stock dividends declared each quarter (in dollars per share) | $ 0.06 | $ 0.06 | $ 0.06
Class B [Member] |  |  |
Class of Stock [Line Items] |  |  |
Common stock dividends declared each quarter (in dollars per share) | $ 0.07 | $ 0.07 | $ 0.07

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