REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) month	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Disaggregation of Revenue [Line Items]
Early termination revenue	$ 49,500	$ 800	$ 57,800	$ 9,100
Contract drilling services	314,405	684,788	1,556,093	2,139,798
Capitalized cost	6,300		$ 6,300		$ 13,900
Number of months of unsatisfied performance obligations represent in our backlog relating to contract that currently contain month-to-month terms | month			1
Notification Fee
Disaggregation of Revenue [Line Items]
Contract drilling services	$ 900	$ 800	$ 3,000	$ 1,000