PENSION AND POST RETIREMENT BENEFIT PLANS (Details) - USD ($) $ in Thousands  | 
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017  | 
Sep. 30, 2016  | 
Sep. 30, 2017  | 
Sep. 30, 2016  | 
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| Components of net periodic pension benefit Gain | ||||
| Interest and service cost | $ 2,138 | $ 2,350 | $ 6,414 | $ 7,050 | 
| Expected return on plan assets | (3,342) | (3,305) | (10,026) | (9,915) | 
| Amortization of net loss | 830 | 816 | 2,490 | 2,448 | 
| Net periodic loss/(benefit) | $ (374) | $ (139) | $ (1,122) | $ (417) | 
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- Definition Defined Benefit Plan Interest and Service Cost No definition available. 
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- References No definition available. 
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