BUSINESS SEGMENTS AND GEOGRAPHIC INFORMATION - Total Assets by Reportable Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Assets	$ 4,334,350	$ 5,034,128
Operating Segment
Segment Reporting Information [Line Items]
Assets	3,939,262	3,868,367
Investments and corporate operations
Segment Reporting Information [Line Items]
Assets	395,088	1,165,761
North America Solutions | Operating Segment
Segment Reporting Information [Line Items]
Assets	3,365,225	3,418,569
Offshore Gulf of Mexico | Operating Segment
Segment Reporting Information [Line Items]
Assets	81,575	84,580
International Solutions | Operating Segment
Segment Reporting Information [Line Items]
Assets	386,832	269,820
Other | Operating Segment
Segment Reporting Information [Line Items]
Assets	$ 105,630	$ 95,398