VARIABLE INTEREST ENTITIES - Balance Sheets of VIEs (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 117,848	$ 96,656	$ 71,159	$ 104,310
Accounts receivable	214,779	206,915
Inventories	133,993	124,911
Prepaid expenses and other current assets	43,668	41,143
Total current assets	541,326	507,871
Investment in unconsolidated affiliates	211,115	210,162
Property and equipment, net	2,079,184	2,254,364
Goodwill	20,299	19,798
Other assets	115,233	121,652
Total assets	2,967,157	3,113,847
Accounts payable	87,428	98,215
Accrued liabilities	192,041	186,246
Accrued interest	6,292	12,909
Short-term borrowings and current maturities of long-term debt	93,136	131,063
Total current liabilities	372,605	416,354
Long-term debt, less current maturities	1,102,765	1,150,956
Accrued pension liabilities	54,291	61,647
Other liabilities and deferred credits	37,768	28,899
Deferred taxes	141,904
Deferred taxes		154,873
Redeemable noncontrolling interest	3,859	6,886
Bristow Aviation Holdings Limited
Variable Interest Entity [Line Items]
Cash and cash equivalents	84,236	92,409
Accounts receivable	271,053	222,560
Inventories	102,370	90,190
Prepaid expenses and other current assets	48,016	50,016
Total current assets	505,675	455,175
Investment in unconsolidated affiliates	3,407	3,513
Property and equipment, net	318,879	306,831
Goodwill	20,299	19,798
Other assets	208,390	203,228
Total assets	1,056,650	988,545
Accounts payable	276,997	146,841
Accrued liabilities	142,180	122,130
Accrued interest	2,065,246	1,891,305
Short-term borrowings and current maturities of long-term debt	20,993	18,578
Total current liabilities	2,505,416	2,178,854
Long-term debt, less current maturities	465,699	501,782
Accrued pension liabilities	54,291	61,647
Other liabilities and deferred credits	2,495	8,138
Deferred taxes	16,777
Deferred taxes		20,264
Redeemable noncontrolling interest	3,859	6,886
Liabilities	$ 3,048,537	$ 2,777,571