PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 2) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	$ 210,556	$ 225,862
U.S. equity securities
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	110,705	115,102
Non-U.S. equity securities
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	20,866	22,081
Fixed income funds and cash investment funds
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	78,985	88,679
Level 1
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	210,556	225,862
Level 1 | U.S. equity securities
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	110,705	115,102
Level 1 | Non-U.S. equity securities
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	20,866	22,081
Level 1 | Fixed income funds and cash investment funds
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Fair value of pension plan investments	$ 78,985	$ 88,679