QUARTERLY FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Unusual or Infrequent Item [Line Items]
Gross revenue	$ 358,442	$ 360,735	$ 373,676	$ 352,109	$ 336,194	$ 337,443	$ 357,467	$ 369,398	$ 1,444,962	$ 1,400,502	$ 1,715,513
Operating income (loss)	(107,835)	(3,497)	(12,917)	(24,589)	(19,528)	(19,097)	(26,882)	(26,235)	(148,838)	(91,742)	(40,845)
Net income (loss) attributable to Bristow Group	$ (100,901)	$ (8,273)	$ (31,209)	$ (55,275)	$ (78,040)	$ (21,927)	$ (29,797)	$ (40,772)	$ (195,658)	$ (170,536)	$ (72,442)
Basic loss per common share	$ (2.84)	$ (0.23)	$ (0.88)	$ (1.57)	$ (2.22)	$ (0.62)	$ (0.85)	$ (1.17)	$ (5.54)	$ (4.87)	$ (2.12)
Diluted loss per common share	$ (2.84)	$ (0.23)	$ (0.88)	$ (1.57)	$ (2.22)	$ (0.62)	$ (0.85)	$ (1.17)	$ (5.54)	$ (4.87)	$ (2.12)
Organizational restructuring
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss	$ (8,500)	$ (2,800)	$ (2,700)	$ (9,700)	$ (2,800)	$ (800)	$ (10,700)	$ (6,600)
Unusual or infrequent item, net income impact, net	$ (6,000)	$ (2,500)	$ (2,200)	$ (6,600)	$ (2,100)	$ (600)	$ (7,300)	$ (4,300)
Unusual or infrequent item, earnings per share impact, net	$ (0.17)	$ (0.07)	$ (0.06)	$ (0.19)	$ (0.06)	$ (0.02)	$ (0.21)	$ (0.12)
Inventory impairment
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss				$ (1,200)			$ (7,600)
Unusual or infrequent item, net income impact, net				$ (800)			$ (5,300)
Unusual or infrequent item, earnings per share impact, net				$ (0.02)			$ (0.15)
Accelerated depreciation
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss					$ (1,100)	$ (1,100)	$ (1,300)	$ (6,900)
Unusual or infrequent item, net income impact, net					$ (700)	$ (800)	$ (900)	$ (4,500)
Unusual or infrequent item, earnings per share impact, net					$ (0.02)	$ (0.02)	$ (0.02)	$ (0.13)
Impairment of goodwill
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss						$ (8,700)
Unusual or infrequent item, net income impact, net						$ (7,900)
Unusual or infrequent item, earnings per share impact, net						$ (0.22)
Reversal of contingent consideration
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss					$ 5,900
Unusual or infrequent item, net income impact, net					$ 5,900
Unusual or infrequent item, earnings per share impact, net					$ 0.17
Tax items
Unusual or Infrequent Item [Line Items]
Unusual or infrequent item, net income impact, net	$ 25,800	$ 15,100	$ (3,200)	$ (14,900)	$ (40,000)	$ (3,700)	$ (2,500)	$ (13,200)
Unusual or infrequent item, earnings per share impact, net	$ 0.73	$ 0.42	$ (0.09)	$ (0.42)	$ (1.14)	$ (0.10)	$ (0.07)	$ (0.38)
Loss on impairment
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss	$ (90,200)
Unusual or infrequent item, net income impact, net	$ (62,400)
Unusual or infrequent item, earnings per share impact, net	$ (1.76)
Repurchase of debt
Unusual or Infrequent Item [Line Items]
Unusual or infrequent item, net income impact, net	$ (1,300)
Unusual or infrequent item, earnings per share impact, net	$ (0.04)
Disposal of assets
Unusual or Infrequent Item [Line Items]
Unusual or Infrequent Item, or Both, Net (Gain) Loss	$ (5,200)	$ (4,600)	$ (8,500)	$ 700	$ (1,400)	$ (900)	$ (2,200)	$ (10,000)
Unusual or infrequent item, net income impact, net	$ (40,100)	$ (2,500)	$ (14,100)	$ (3,900)	$ (800)	$ 1,100	$ (1,500)	$ (6,800)
Unusual or infrequent item, earnings per share impact, net	$ (1.13)	$ (0.07)	$ (0.40)	$ (0.11)	$ (0.02)	$ 0.03