BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Capital expenditures	$ 18,511	$ 8,407	$ 25,950	$ 17,302
Aircraft and equipment
Property, Plant and Equipment [Line Items]
Capital expenditures	16,074	4,394	22,762	12,731
Land and buildings
Property, Plant and Equipment [Line Items]
Capital expenditures	$ 2,437	$ 4,013	$ 3,188	$ 4,571