RESTRUCTURING CHARGES - Summary of Restructuring and Other Similar Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 5,926	$ 16,047
Operating Segments \| North America Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	3,869	7,005
Operating Segments \| Offshore Gulf of Mexico
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		1,254
Operating Segments \| International Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	207	2,980
Operating Segments \| Other
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		260
Corporate G&A
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,850	4,548
Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,476	19,530
Employee termination benefits \| Operating Segments \| North America Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	54	10,041
Employee termination benefits \| Operating Segments \| Offshore Gulf of Mexico
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		1,432
Employee termination benefits \| Operating Segments \| International Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	207	2,991
Employee termination benefits \| Operating Segments \| Other
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		321
Employee termination benefits \| Corporate G&A
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,215	4,745
Other restructuring expenses
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	4,450
Other restructuring expenses \| Operating Segments \| North America Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	3,815
Other restructuring expenses \| Operating Segments \| International Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	0
Other restructuring expenses \| Corporate G&A
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 635
Stock-based compensation benefit
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		(3,483)
Stock-based compensation benefit \| Operating Segments \| North America Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		(3,036)
Stock-based compensation benefit \| Operating Segments \| Offshore Gulf of Mexico
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		(178)
Stock-based compensation benefit \| Operating Segments \| International Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		(11)
Stock-based compensation benefit \| Operating Segments \| Other
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		(61)
Stock-based compensation benefit \| Corporate G&A
Restructuring Cost and Reserve [Line Items]
Total restructuring charges		$ (197)