PROPERTY, PLANT AND EQUIPMENT - Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment
Depreciation	$ 583,802	$ 585,543	$ 598,587
Abandonments	27,700	42,600	39,300
Net book value	4,857,382	$ 5,001,051	$ 5,144,733
Rigs components depreciation
Property, Plant and Equipment
Net book value	3,700
Increase in depreciation	9,700
Remainder of fiscal year	900
2019	(2,300)
2020	(2,300)
2021	(2,200)
2022	(1,300)
2023	(400)
Thereafter	$ (1,000)