OPERATIONS, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Immaterial Corrections to Prior Period Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Investment in unconsolidated affiliates	$ 118,203				$ 131,527				$ 118,203	$ 131,527
Retained earnings	455,598				794,191				455,598	794,191
Total Bristow Group stockholders’ investment	805,219				1,176,248				805,219	1,176,248
Total stockholders’ investment	812,367				1,183,501				812,367	1,183,501	$ 1,293,666	$ 1,508,352
Revenues	323,793	$ 329,858	$ 349,343	$ 366,668	356,384	$ 357,985	$ 370,901	$ 348,705	1,369,662	1,433,975	1,388,082
Earnings from unconsolidated affiliates, net of losses									4,317	18,699	20,339
Operating loss	(53,403)	(30,919)	(129,448)	(3,555)	(107,623)	(3,283)	(12,703)	(24,374)	(217,325)	(147,983)	(89,871)
Loss before benefit (provision) for income taxes									(336,299)	(228,000)	(143,328)
Net loss									(336,138)	(197,109)	(175,916)
Net income (loss) attributable to Bristow Group	$ (75,336)	$ (85,699)	$ (143,947)	$ (31,865)	$ (100,658)	$ (8,030)	$ (30,965)	$ (55,031)	$ (336,847)	$ (194,684)	$ (169,562)
Basic loss per common share	$ (2.10)	$ (2.39)	$ (4.02)	$ (0.89)	$ (2.84)	$ (0.23)	$ (0.88)	$ (1.56)	$ (9.42)	$ (5.52)	$ (4.84)
Diluted loss per common share	$ (2.10)	$ (2.39)	$ (4.02)	$ (0.89)	$ (2.84)	$ (0.23)	$ (0.88)	$ (1.56)	$ (9.42)	$ (5.52)	$ (4.84)
Total comprehensive loss									$ (377,853)	$ (159,195)	$ (209,063)
Total comprehensive loss attributable to Bristow Group									$ (378,742)	(152,501)	(208,020)
Cougar Helicopters Purchase Price Accounting Issue [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Investment in unconsolidated affiliates					$ 131,527					131,527
Retained earnings					794,191					794,191
Total Bristow Group stockholders’ investment					1,176,248					1,176,248
Total stockholders’ investment					1,183,501					1,183,501
Revenues										1,433,975	1,388,082
Earnings from unconsolidated affiliates, net of losses										18,699	20,339
Operating loss										(147,983)	(89,871)
Loss before benefit (provision) for income taxes										(228,000)	(143,328)
Net loss										(197,109)	(175,916)
Net income (loss) attributable to Bristow Group										$ (194,684)	$ (169,562)
Basic loss per common share										$ (5,520)	$ (4,840)
Diluted loss per common share										$ (5,520)	$ (4,840)
Total comprehensive loss										$ (159,195)	$ (209,063)
Total comprehensive loss attributable to Bristow Group										$ (152,501)	(208,020)
Cougar Helicopters Purchase Price Accounting Issue [Member] | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life										20 years
Investment in unconsolidated affiliates					126,170					$ 126,170
Retained earnings					788,834					788,834
Total Bristow Group stockholders’ investment					1,170,891					1,170,891
Total stockholders’ investment					1,178,144					1,178,144
Revenues										1,444,962	1,400,502
Earnings from unconsolidated affiliates, net of losses										6,738	6,945
Operating loss										(148,957)	(90,845)
Loss before benefit (provision) for income taxes										(228,974)	(144,302)
Net loss										(198,083)	(176,890)
Net income (loss) attributable to Bristow Group										$ (195,658)	$ (170,536)
Basic loss per common share										$ (5,540)	$ (4,870)
Diluted loss per common share										$ (5,540)	$ (4,870)
Total comprehensive loss										$ (160,169)	$ (210,037)
Total comprehensive loss attributable to Bristow Group										(153,475)	(208,994)
Cougar Helicopters Purchase Price Accounting Issue [Member] | Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Investment in unconsolidated affiliates					5,357					5,357
Retained earnings					5,357					5,357	4,400	$ 3,400
Total Bristow Group stockholders’ investment					5,357					5,357
Total stockholders’ investment					$ 5,357					5,357
Revenues										(10,987)	(12,420)
Earnings from unconsolidated affiliates, net of losses										11,961	13,394
Operating loss										974	974
Loss before benefit (provision) for income taxes										974	974
Net loss										974	974
Net income (loss) attributable to Bristow Group										$ 974	$ 974
Basic loss per common share										$ 20	$ 30
Diluted loss per common share										$ 20	$ 30
Total comprehensive loss										$ 974	$ 974
Total comprehensive loss attributable to Bristow Group										$ 974	$ 974