SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Condensed Financial Statements, Captions [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
Assets held for sale	31,038	38,246
Prepaid expenses and other current assets	43,668	41,143
Total current assets	541,326	507,871
Intercompany investment	0	0
Investment in unconsolidated affiliates	211,115	210,162
Intercompany notes receivable	0	0
Land and buildings	241,792	231,448
Aircraft and equipment	2,511,322	2,622,701
Total property and equipment, at cost	2,753,114	2,854,149
Less – Accumulated depreciation and amortization	(673,930)	(599,785)
Total 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
Deferred taxes		830
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
Intercompany notes payable	0	0
Accrued pension liabilities	54,291	61,647
Other liabilities and deferred credits	37,768	28,899
Deferred taxes		154,873
Deferred taxes	141,904
Redeemable noncontrolling interest	3,859	6,886
Common stock	381	379
Additional paid-in capital	844,825	809,995
Retained earnings	894,684	991,906
Accumulated other comprehensive income (loss)	(307,353)	(328,277)
Treasury shares	(184,796)	(184,796)
Total Bristow Group stockholders’ investment	1,247,741	1,289,207
Noncontrolling interests	6,224	5,025
Total stockholders’ investment	1,253,965	1,294,232
Total liabilities, redeemable noncontrolling interest and stockholders’ investment	2,967,157	3,113,847
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	(922)	0	(2,947)	0
Accounts receivable	(674,071)	(370,603)
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	0	(10,451)
Total current assets	(674,993)	(381,054)
Intercompany investment	(2,628,444)	(2,722,362)
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	(360,274)	(383,980)
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	(21)	0
Total assets	(3,663,732)	(3,487,396)
Accounts payable	(655,787)	(355,442)
Accrued liabilities	(17,975)	(25,628)
Deferred taxes		0
Short-term borrowings and current maturities of long-term debt	0	0
Total current liabilities	(673,762)	(381,070)
Long-term debt, less current maturities	0	0
Intercompany notes payable	(361,375)	(383,980)
Accrued pension liabilities	0	0
Other liabilities and deferred credits	0	0
Deferred taxes		0
Deferred taxes	(21)
Redeemable noncontrolling interest	0	0
Common stock	(151,345)	(135,345)
Additional paid-in capital	(329,354)	(313,435)
Retained earnings	(1,475,495)	(1,611,104)
Accumulated other comprehensive income (loss)	(672,380)	(662,462)
Treasury shares	0	0
Total Bristow Group stockholders’ investment	(2,628,574)	(2,722,346)
Noncontrolling interests	0	0
Total stockholders’ investment	(2,628,574)	(2,722,346)
Total liabilities, redeemable noncontrolling interest and stockholders’ investment	(3,663,732)	(3,487,396)
Parent Company Only
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	27,895	3,382	2,397	35,241
Accounts receivable	148,115	76,383
Inventories	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	2,427	3,237
Total current assets	178,437	83,002
Intercompany investment	2,387,382	2,491,631
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	166,341	306,641
Land and buildings	4,806	4,806
Aircraft and equipment	157,421	151,005
Total property and equipment, at cost	162,227	155,811
Less – Accumulated depreciation and amortization	(38,062)	(29,099)
Total property and equipment, net	124,165	126,712
Goodwill	0	0
Other assets	9,471	18,770
Total assets	2,865,796	3,026,756
Accounts payable	348,871	231,841
Accrued liabilities	48,284	61,791
Deferred taxes		(1,272)
Short-term borrowings and current maturities of long-term debt	40,087	79,053
Total current liabilities	437,242	371,413
Long-term debt, less current maturities	513,801	763,325
Intercompany notes payable	187,531	70,689
Accrued pension liabilities	0	0
Other liabilities and deferred credits	13,570	11,597
Deferred taxes		112,716
Deferred taxes	78,937
Redeemable noncontrolling interest	0	0
Common stock	381	379
Additional paid-in capital	844,825	809,995
Retained earnings	894,684	991,906
Accumulated other comprehensive income (loss)	78,306	78,306
Treasury shares	(184,796)	(184,796)
Total Bristow Group stockholders’ investment	1,633,400	1,695,790
Noncontrolling interests	1,315	1,226
Total stockholders’ investment	1,634,715	1,697,016
Total liabilities, redeemable noncontrolling interest and stockholders’ investment	2,865,796	3,026,756
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	299	0	3,393
Accounts receivable	419,838	288,235
Inventories	31,623	34,721
Assets held for sale	25,265	30,716
Prepaid expenses and other current assets	5,234	4,501
Total current assets	481,960	358,472
Intercompany investment	104,435	104,435
Investment in unconsolidated affiliates	0	0
Intercompany notes receivable	36,358	37,633
Land and buildings	58,252	62,114
Aircraft and equipment	1,135,071	1,199,073
Total property and equipment, at cost	1,193,323	1,261,187
Less – Accumulated depreciation and amortization	(257,033)	(258,225)
Total property and equipment, net	936,290	1,002,962
Goodwill	0	0
Other assets	1,961	2,139
Total assets	1,561,004	1,505,641
Accounts payable	203,517	70,434
Accrued liabilities	4,391	17,379
Deferred taxes		2,102
Short-term borrowings and current maturities of long-term debt	20,335	17,432
Total current liabilities	228,243	107,347
Long-term debt, less current maturities	277,442	284,710
Intercompany notes payable	133,087	226,091
Accrued pension liabilities	0	0
Other liabilities and deferred credits	7,660	6,229
Deferred taxes		40,344
Deferred taxes	47,494
Redeemable noncontrolling interest	0	0
Common stock	20,028	20,028
Additional paid-in capital	45,306	29,387
Retained earnings	800,730	791,117
Accumulated other comprehensive income (loss)	1,014	388
Treasury shares	0	0
Total Bristow Group stockholders’ investment	867,078	840,920
Noncontrolling interests	0	0
Total stockholders’ investment	867,078	840,920
Total liabilities, redeemable noncontrolling interest and stockholders’ investment	1,561,004	1,505,641
Non- Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	90,875	92,975	$ 71,709	$ 65,676
Accounts receivable	320,897	212,900
Inventories	102,370	90,190
Assets held for sale	5,773	7,530
Prepaid expenses and other current assets	36,007	43,856
Total current assets	555,922	447,451
Intercompany investment	136,627	126,296
Investment in unconsolidated affiliates	211,115	210,162
Intercompany notes receivable	157,575	39,706
Land and buildings	178,734	164,528
Aircraft and equipment	1,218,830	1,272,623
Total property and equipment, at cost	1,397,564	1,437,151
Less – Accumulated depreciation and amortization	(378,835)	(312,461)
Total property and equipment, net	1,018,729	1,124,690
Goodwill	20,299	19,798
Other assets	103,822	100,743
Total assets	2,204,089	2,068,846
Accounts payable	190,827	151,382
Accrued liabilities	157,341	132,704
Deferred taxes		0
Short-term borrowings and current maturities of long-term debt	32,714	34,578
Total current liabilities	380,882	318,664
Long-term debt, less current maturities	311,522	102,921
Intercompany notes payable	40,757	87,200
Accrued pension liabilities	54,291	61,647
Other liabilities and deferred credits	16,538	11,073
Deferred taxes		1,813
Deferred taxes	15,494
Redeemable noncontrolling interest	3,859	6,886
Common stock	131,317	115,317
Additional paid-in capital	284,048	284,048
Retained earnings	674,765	819,987
Accumulated other comprehensive income (loss)	285,707	255,491
Treasury shares	0	0
Total Bristow Group stockholders’ investment	1,375,837	1,474,843
Noncontrolling interests	4,909	3,799
Total stockholders’ investment	1,380,746	1,478,642
Total liabilities, redeemable noncontrolling interest and stockholders’ investment	$ 2,204,089	$ 2,068,846