SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 316,550	$ 380,223	$ 78,879	$ 96,656
Accounts receivable	259,800	246,980
Inventories	125,681	129,614
Assets held for sale	23,502	30,348
Prepaid expenses and other current assets	49,584	47,234
Total current assets	775,117	834,399
Intercompany investment	0	0
Investment in unconsolidated affiliates	114,609	126,170
Intercompany notes receivable	0	0
Land and buildings	242,068	250,040
Aircraft and equipment	2,493,370	2,511,131
Total property and equipment, at cost	2,735,438	2,761,171
Less – Accumulated depreciation and amortization	(715,496)	(693,151)
Total property and equipment, net	2,019,942	2,068,020
Goodwill	19,175	19,907
Other assets	118,955	116,506
Total assets	3,047,798	3,165,002
Accounts payable	100,299	101,270
Accrued liabilities	185,576	209,876
Short-term borrowings and current maturities of long-term debt	1,453,423	1,475,438
Total current liabilities	1,739,298	1,786,584
Long-term debt, less current maturities	10,383	11,096
Intercompany notes payable	0	0
Accrued pension liabilities	30,526	37,034
Other liabilities and deferred credits	32,302	36,952
Deferred taxes	114,645	115,192
Common stock	385	382
Additional paid-in capital	856,826	852,565
Retained earnings	754,980	788,834
Accumulated other comprehensive income (loss)	(313,918)	(286,094)
Treasury shares	(184,796)	(184,796)
Total Bristow Group stockholders’ investment	1,113,477	1,170,891
Noncontrolling interests	7,167	7,253
Total stockholders’ investment	1,120,644	1,178,144
Total liabilities and stockholders’ investment	3,047,798	3,165,002
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Accounts receivable	(952,282)	(638,630)
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	0	(1,643)
Total current assets	(952,282)	(640,273)
Intercompany investment	(2,265,555)	(2,445,623)
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	(366,755)	(588,567)
Land and buildings	0	0
Aircraft and equipment	0	0
Total property and equipment, at cost	0	0
Less – Accumulated depreciation and amortization	0	0
Total property and equipment, net	0	0
Goodwill	0	0
Other assets	0	0
Total assets	(3,584,592)	(3,674,463)
Accounts payable	(930,361)	(616,909)
Accrued liabilities	(20,573)	(21,955)
Short-term borrowings and current maturities of long-term debt	0	0
Total current liabilities	(950,934)	(638,864)
Long-term debt, less current maturities	0	0
Intercompany notes payable	(367,857)	(544,148)
Accrued pension liabilities	0	0
Other liabilities and deferred credits	0	0
Deferred taxes	0	0
Common stock	(136,313)	(136,313)
Additional paid-in capital	(313,435)	(313,435)
Retained earnings	(1,140,444)	(1,312,439)
Accumulated other comprehensive income (loss)	(675,609)	(729,264)
Treasury shares	0	0
Total Bristow Group stockholders’ investment	(2,265,801)	(2,491,451)
Noncontrolling interests	0	0
Total stockholders’ investment	(2,265,801)	(2,491,451)
Total liabilities and stockholders’ investment	(3,584,592)	(3,674,463)
Parent Company Only
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	244,990	277,176	5,386	3,382
Accounts receivable	421,367	211,412
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	2,453	3,367
Total current assets	668,810	491,955
Intercompany investment	2,027,774	2,199,505
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	170,513	183,634
Land and buildings	4,806	4,806
Aircraft and equipment	156,500	156,651
Total property and equipment, at cost	161,306	161,457
Less – Accumulated depreciation and amortization	(42,846)	(39,780)
Total property and equipment, net	118,460	121,677
Goodwill	0	0
Other assets	4,221	4,966
Total assets	2,989,778	3,001,737
Accounts payable	374,301	341,342
Accrued liabilities	51,808	59,070
Short-term borrowings and current maturities of long-term debt	842,258	840,485
Total current liabilities	1,268,367	1,240,897
Long-term debt, less current maturities	0	0
Intercompany notes payable	133,078	132,740
Accrued pension liabilities	0	0
Other liabilities and deferred credits	12,042	14,078
Deferred taxes	69,311	77,373
Common stock	385	382
Additional paid-in capital	856,826	852,565
Retained earnings	754,980	788,834
Accumulated other comprehensive income (loss)	78,306	78,306
Treasury shares	(184,796)	(184,796)
Total Bristow Group stockholders’ investment	1,505,701	1,535,291
Noncontrolling interests	1,279	1,358
Total stockholders’ investment	1,506,980	1,536,649
Total liabilities and stockholders’ investment	2,989,778	3,001,737
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,514	8,904	1,187	299
Accounts receivable	492,437	423,214
Inventories	33,018	31,300
Assets held for sale	19,856	26,737
Prepaid expenses and other current assets	5,115	4,494
Total current assets	551,940	494,649
Intercompany investment	104,435	104,435
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	36,358	36,358
Land and buildings	58,089	58,191
Aircraft and equipment	1,318,149	1,326,922
Total property and equipment, at cost	1,376,238	1,385,113
Less – Accumulated depreciation and amortization	(279,325)	(263,412)
Total property and equipment, net	1,096,913	1,121,701
Goodwill	0	0
Other assets	1,357	2,122
Total assets	1,791,003	1,759,265
Accounts payable	405,656	175,133
Accrued liabilities	2,607	6,735
Short-term borrowings and current maturities of long-term debt	284,994	296,782
Total current liabilities	693,257	478,650
Long-term debt, less current maturities	0	0
Intercompany notes payable	197,397	370,407
Accrued pension liabilities	0	0
Other liabilities and deferred credits	7,635	7,924
Deferred taxes	26,726	27,794
Common stock	4,996	4,996
Additional paid-in capital	29,387	29,387
Retained earnings	831,111	838,727
Accumulated other comprehensive income (loss)	494	1,380
Treasury shares	0	0
Total Bristow Group stockholders’ investment	865,988	874,490
Noncontrolling interests	0	0
Total stockholders’ investment	865,988	874,490
Total liabilities and stockholders’ investment	1,791,003	1,759,265
Non- Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	70,046	94,143	$ 72,306	$ 92,975
Accounts receivable	298,278	250,984
Inventories	92,663	98,314
Assets held for sale	3,646	3,611
Prepaid expenses and other current assets	42,016	41,016
Total current assets	506,649	488,068
Intercompany investment	133,346	141,683
Investment in unconsolidated affiliates	114,609	126,170
Intercompany notes receivable	159,884	368,575
Land and buildings	179,173	187,043
Aircraft and equipment	1,018,721	1,027,558
Total property and equipment, at cost	1,197,894	1,214,601
Less – Accumulated depreciation and amortization	(393,325)	(389,959)
Total property and equipment, net	804,569	824,642
Goodwill	19,175	19,907
Other assets	113,377	109,418
Total assets	1,851,609	2,078,463
Accounts payable	250,703	201,704
Accrued liabilities	151,734	166,026
Short-term borrowings and current maturities of long-term debt	326,171	338,171
Total current liabilities	728,608	705,901
Long-term debt, less current maturities	10,383	11,096
Intercompany notes payable	37,382	41,001
Accrued pension liabilities	30,526	37,034
Other liabilities and deferred credits	12,625	14,950
Deferred taxes	18,608	10,025
Common stock	131,317	131,317
Additional paid-in capital	284,048	284,048
Retained earnings	309,333	473,712
Accumulated other comprehensive income (loss)	282,891	363,484
Treasury shares	0	0
Total Bristow Group stockholders’ investment	1,007,589	1,252,561
Noncontrolling interests	5,888	5,895
Total stockholders’ investment	1,013,477	1,258,456
Total liabilities and stockholders’ investment	$ 1,851,609	$ 2,078,463