PENSION BENEFIT PLANS - Net Periodic Pension Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retirement Benefits [Abstract]
Service cost	$ 63	$ 70	$ 126	$ 141
Interest cost	123	136	244	273
Net periodic pension cost	$ 186	$ 206	$ 370	$ 414