BASIS OF PRESENTATION, CONSOLIDATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	1 Months Ended		2 Months Ended	3 Months Ended			9 Months Ended
	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($) aircraft	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) aircraft	Mar. 31, 2017 USD ($)
Item Affected [Line Items]
Allowance for doubtful accounts receivable		$ 3,800,000		$ 3,800,000			$ 3,800,000		$ 4,500,000
Inventory allowance		22,100,000		22,100,000			22,100,000		21,500,000
Inventory write-down				0		$ 0	1,192,000	$ 7,572,000
Short-term portion of contract acquisition and pre-operating costs		10,700,000		10,700,000			10,700,000		9,700,000
Amortization of other deferred charges				2,800,000		2,500,000	8,500,000	8,200,000
Goodwill, Impairment Loss						8,706,000	0	8,706,000
Goodwill		20,299,000		20,299,000			20,299,000		19,798,000
Accumulated goodwill impairment		50,861,000		50,861,000			50,861,000		50,861,000
Long-term portion of contract acquisition and pre-operating costs		51,200,000		51,200,000			51,200,000		51,100,000
Impairment charges on aircraft held for sale				1,560,000		200,000	11,307,000	11,360,000
Accelerated depreciation						$ 1,100,000		$ 9,300,000
Number of aircraft in exit plan | aircraft						5		11
Deferred OEM cost recovery		$ 10,413,000		$ 10,413,000			$ 10,413,000		0
Property, Plant and Equipment, Salvage Value, Percentage		50.00%		50.00%			50.00%
Other accrued liabilities		$ 72,292,000		$ 72,292,000			$ 72,292,000		46,679,000
Current deferred tax assets									100,000
Current deferred tax liabilities									800,000
Payments Related to Tax Withholding for Share-based Compensation							591,000	$ 762,000
Adjustments for new accounting pronouncement
Item Affected [Line Items]
Increase to income tax provision							2,300,000
OEM Cost recoveries
Item Affected [Line Items]
Original Equipment Manufacturer, Recoveries Sought				130,000,000			130,000,000
Original Equipment Manufacturer, Amount Received				125,000,000			125,000,000
Accumulated Depreciation, Period Increase (Decrease)			$ 94,500,000	94,500,000
Deferred OEM cost recovery		17,400,000	18,500,000	17,400,000			17,400,000
OEM Cost recoveries | Depreciation Expense [Member]
Item Affected [Line Items]
Offset Amount, Expense, Remainder of Fiscal Year		2,100,000		2,100,000			2,100,000
Offset Amount, Expense, Rolling Year Two		8,500,000		8,500,000			8,500,000
Offset Amount, Expense, Rolling Year Three		8,400,000		8,400,000			8,400,000
Offset Amount, Expense, Rolling Year Four		5,600,000		5,600,000			5,600,000
Offset Amount, Expense, Rolling Year Five and Thereafter		21,300,000		21,300,000			21,300,000
OEM Cost recoveries | Rent Expense
Item Affected [Line Items]
Offset Amount, Expense		1,100,000	$ 12,000,000	13,100,000			13,100,000
Offset Amount, Expense, Remainder of Fiscal Year		3,500,000		3,500,000			3,500,000
Offset Amount, Expense, Rolling Year Two		7,900,000		7,900,000			7,900,000
Offset Amount, Expense, Rolling Year Three		4,000,000		4,000,000			4,000,000
Offset Amount, Expense, Rolling Year Four		2,000,000		2,000,000			2,000,000
Affiliated entity
Item Affected [Line Items]
Allowance for doubtful accounts receivable		$ 0		$ 0			$ 0		$ 0
Eastern Airways | Subsequent Event
Item Affected [Line Items]
Consolidation, Additional Percentage Purchased Subsidiary	40.00%
Changes in purchase of interest by parent	$ 0.0
Held-for-sale | Bristow Academy
Item Affected [Line Items]
Percentage ownership disposed		100.00%		100.00%			100.00%
Disposal Group, Including Discontinued Operation, Consideration		$ 1,500,000		$ 1,500,000			$ 1,500,000
Disposal Group, Consideration Term							4 years
Impairment charges on aircraft held for sale					$ 6,500,000		$ 6,500,000
Disposal group, not discontinued operation, loss on disposal				$ 700,000