PROPERTY, PLANT AND EQUIPMENT - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 7,492,361	$ 7,477,539
Accumulated depreciation	(4,561,060)	(4,516,730)
Property, plant and equipment, net	2,931,301	2,960,809
Assets held-for-sale	1,349	4,333
Drilling services equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 6,338,257	6,369,888
Drilling services equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Drilling services equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Tubulars
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Property, plant and equipment, gross	$ 571,945	569,496
Real estate properties
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 46,293	45,557
Real estate properties | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Real estate properties | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 436,243	422,479
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	23 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 99,623	$ 70,119