DEBT - Narrative (Details) $ in Thousands	6 Months Ended
	Sep. 30, 2018 USD ($) subsidiary	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Total debt	$ 1,474,539	$ 1,513,999
Revolving Credit Facility | ABL Facility
Debt Instrument [Line Items]
Line Of Credit Facility, Number Of Borrowers | subsidiary	2
Line of Credit Facility, Current Borrowing Capacity	$ 75,000
Line Of Credit Facility, Availability Block Capacity	15,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 100,000
Terms of debt instruments	5 years
Letters of Credit Outstanding, Amount	$ 11,400
Total debt	0
Other Debt | Eastern Airways Debt
Debt Instrument [Line Items]
Total debt	$ 7,531	$ 14,519
Debt Instrument, Basis Spread on Variable Rate	2.75%
Repayments of Debt	$ 4,900