PROPERTY, PLANT AND EQUIPMENT - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2022	Sep. 30, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 7,417,779	$ 7,353,541
Accumulated depreciation	(4,430,672)	(4,226,254)
Property, plant and equipment, net	2,987,107	3,127,287
Assets held-for-sale	25,604	71,453
Drilling services equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 6,327,863	6,229,011
Drilling services equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	4 years
Drilling services equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	15 years
Tubulars
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	4 years
Property, plant and equipment, gross	$ 573,514	573,900
Real estate properties
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 45,308	43,302
Real estate properties | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	10 years
Real estate properties | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	45 years
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 416,163	459,741
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	2 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	23 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 54,931	$ 47,587