BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018 USD ($) aircraft	Dec. 31, 2017 USD ($) aircraft	Dec. 31, 2018 USD ($) aircraft	Dec. 31, 2017 USD ($) aircraft
Property, Plant and Equipment [Line Items]
Number of aircraft delivered | aircraft	1	0	1	5
Capital expenditures	$ 16,409	$ 12,124	$ 33,711	$ 36,441
Progress payments for aircraft	$ 0	$ 0	$ 0	$ 2,300
Medium
Property, Plant and Equipment [Line Items]
Number of aircraft delivered | aircraft	1	0	1	5
Aircraft and equipment
Property, Plant and Equipment [Line Items]
Capital expenditures	$ 15,839	$ 10,311	$ 28,570	$ 26,800
Land and buildings
Property, Plant and Equipment [Line Items]
Capital expenditures	$ 570	$ 1,813	$ 5,141	$ 9,641