BUSINESS SEGMENTS AND GEOGRAPHIC INFORMATION - Total Assets by Reportable Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Assets	$ 4,322,610	$ 5,034,128
Operating Segment
Segment Reporting Information [Line Items]
Assets	3,933,814	3,868,367
Investments and corporate operations
Segment Reporting Information [Line Items]
Assets	388,796	1,165,761
North America Solutions | Operating Segment
Segment Reporting Information [Line Items]
Assets	3,407,213	3,418,569
Offshore Gulf of Mexico | Operating Segment
Segment Reporting Information [Line Items]
Assets	79,483	84,580
International Solutions | Operating Segment
Segment Reporting Information [Line Items]
Assets	333,776	269,820
Other | Operating Segment
Segment Reporting Information [Line Items]
Assets	$ 113,342	$ 95,398