BUSINESS SEGMENTS AND GEOGRAPHIC INFORMATION - Summary of Financial Information of Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 246,377	$ 614,657
Segment operating income (loss)	(93,223)	31,368
North America Solutions
Segment Reporting Information [Line Items]
Revenues	201,990	524,681
Offshore Gulf of Mexico
Segment Reporting Information [Line Items]
Revenues	32,273	40,255
International Solutions
Segment Reporting Information [Line Items]
Revenues	10,518	46,462
Other
Segment Reporting Information [Line Items]
Revenues	1,596	3,259
Intersegment
Segment Reporting Information [Line Items]
Revenues	(7,122)	(7,740)
Segment operating income (loss)	(2,126)	0
Intersegment | North America Solutions
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment | Offshore Gulf of Mexico
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment | International Solutions
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment | Other
Segment Reporting Information [Line Items]
Revenues	(7,122)	(7,740)
Operating Segment
Segment Reporting Information [Line Items]
Revenues	246,377	614,657
Segment operating income (loss)	(76,558)	60,345
Operating Segment | North America Solutions
Segment Reporting Information [Line Items]
Revenues	201,990	524,681
Segment operating income (loss)	(72,928)	52,139
Operating Segment | Offshore Gulf of Mexico
Segment Reporting Information [Line Items]
Revenues	32,273	40,255
Segment operating income (loss)	2,742	6,328
Operating Segment | International Solutions
Segment Reporting Information [Line Items]
Revenues	10,518	46,462
Segment operating income (loss)	(8,357)	3,115
Operating Segment | Other
Segment Reporting Information [Line Items]
Revenues	8,718	10,999
Segment operating income (loss)	$ 4,111	$ (1,237)