VARIABLE INTEREST ENTITIES - Balance Sheets of VIEs (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 97,343	$ 96,656	$ 100,668	$ 104,310
Accounts receivable	237,872	206,915
Inventories	131,616	124,911
Prepaid expenses and other current assets	44,089	41,143
Total current assets	545,854	507,871
Investment in unconsolidated affiliates	211,499	210,162
Property and equipment, net	2,196,740	2,254,364
Goodwill	20,364	19,798
Other assets	114,066	121,652
Total assets	3,088,523	3,113,847
Accounts payable	97,762	98,215
Accrued liabilities	194,897	186,246
Accrued interest	12,456	12,909
Short-term borrowings and current maturities of long-term debt	113,519	131,063
Total current liabilities	406,178	416,354
Long-term debt, less current maturities	1,198,587	1,150,956
Accrued pension liabilities	57,928	61,647
Other liabilities and deferred credits	31,873	28,899
Deferred taxes	154,927
Deferred taxes		154,873
Redeemable noncontrolling interest	6,002	6,886
Bristow Aviation Holdings Limited
Variable Interest Entity [Line Items]
Cash and cash equivalents	94,068	92,409
Accounts receivable	296,145	222,560
Inventories	98,460	90,190
Prepaid expenses and other current assets	57,008	50,016
Total current assets	545,681	455,175
Investment in unconsolidated affiliates	3,476	3,513
Property and equipment, net	316,980	306,831
Goodwill	20,364	19,798
Other assets	205,483	203,228
Total assets	1,091,984	988,545
Accounts payable	275,440	146,841
Accrued liabilities	137,719	122,130
Accrued interest	2,004,408	1,891,305
Short-term borrowings and current maturities of long-term debt	20,296	18,578
Total current liabilities	2,437,863	2,178,854
Long-term debt, less current maturities	480,835	501,782
Accrued pension liabilities	57,928	61,647
Other liabilities and deferred credits	7,907	8,138
Deferred taxes	14,195
Deferred taxes		20,264
Redeemable noncontrolling interest	6,002	6,886
Liabilities	$ 3,004,730	$ 2,777,571