PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS - SCHEDULE OF ACCUMULATED BENEFIT OBLIGATIONS IN EXCESS OF PLAN ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Projected benefit obligation	$ 709,651	$ 1,030,382
Accumulated benefit obligation	674,017	993,892
Fair value of plan assets	$ 647,402	$ 962,705