COMMON STOCK (Details) $ / shares in Units, $ in Millions	12 Months Ended
	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