BUSINESS SEGMENTS AND GEOGRAPHIC INFORMATION - Revenues from External Customers and Long-Lived Assets by Country (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Operating revenues	$ 208,267	$ 317,364	$ 633,639	$ 614,657	$ 649,050	$ 687,974	$ 720,868	$ 740,598	$ 1,773,927	$ 2,798,490	$ 2,487,268
Property, plant and equipment, net	3,646,341				4,502,084				3,646,341	4,502,084
United States
Segment Reporting Information [Line Items]
Operating revenues									1,626,407	2,585,008	2,247,400
Property, plant and equipment, net	3,562,525				4,269,405				3,562,525	4,269,405
Argentina
Segment Reporting Information [Line Items]
Operating revenues									84,402	165,718	190,038
Property, plant and equipment, net	49,419				132,321				49,419	132,321
Bahrain
Segment Reporting Information [Line Items]
Operating revenues									28,653	11,528	9,525
United Arab Emirates
Segment Reporting Information [Line Items]
Operating revenues									24,716	4,728	0
Colombia
Segment Reporting Information [Line Items]
Operating revenues									6,414	29,757	38,793
Property, plant and equipment, net	21,740				61,757				21,740	61,757
Other Foreign
Segment Reporting Information [Line Items]
Operating revenues									3,335	1,751	$ 1,512
Property, plant and equipment, net	$ 12,657				$ 38,601				$ 12,657	$ 38,601