VARIABLE INTEREST ENTITIES - Balance Sheets of VIEs (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 231,326	$ 380,223	$ 117,848	$ 96,656
Accounts receivable	204,641	233,386
Inventories	115,254	129,614
Prepaid expenses and other current assets	48,646	47,234
Total current assets	635,538	834,399
Investment in unconsolidated affiliates	113,974	126,170
Property and equipment, net	1,847,543	2,068,020
Goodwill	18,271	19,907
Other assets	116,418	116,506
Total assets	2,731,744	3,165,002
Accounts payable	91,916	101,270
Accrued liabilities	156,465	209,876
Accrued interest	18,317	16,345
Short-term borrowings and current maturities of long-term debt	1,421,050	1,475,438
Total current liabilities	1,669,431	1,786,584
Long-term debt, less current maturities	9,174	11,096
Accrued pension liabilities	28,036	37,034
Other liabilities and deferred credits	28,573	36,952
Deferred taxes	119,057	115,192
Bristow Aviation Holdings Limited
Variable Interest Entity [Line Items]
Cash and cash equivalents	76,432	90,788
Accounts receivable	303,108	256,735
Inventories	80,596	98,314
Prepaid expenses and other current assets	39,009	38,665
Total current assets	499,145	484,502
Investment in unconsolidated affiliates	2,930	3,608
Property and equipment, net	278,562	327,440
Goodwill	18,271	19,907
Other assets	219,636	231,884
Total assets	1,018,544	1,067,341
Accounts payable	413,998	292,893
Accrued liabilities	106,811	140,733
Accrued interest	2,330,164	2,130,433
Short-term borrowings and current maturities of long-term debt	7,963	23,125
Total current liabilities	2,858,936	2,587,184
Long-term debt, less current maturities	460,019	479,571
Accrued pension liabilities	28,036	37,034
Other liabilities and deferred credits	5,521	7,342
Deferred taxes	29,431	26,252
Liabilities	$ 3,381,943	$ 3,137,383