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Number of tranches in a share based payment arrangement.

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Represents the performance cycle of each tranche in a share based payment arrangement.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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STOCK-BASED COMPENSATION - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) component tranche shares	Jun. 30, 2019 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 7,624	$ 8,878	$ 28,576	$ 25,467
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested			0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested			200.00%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 422	719	$ 1,409	3,073
Number of options exercised (in shares) \| shares	0		202,000
Total intrinsic value of options exercised		300	$ 300	7,900
Unrecognized compensation cost related to stock options	$ 1,600		$ 1,600
Weighted average period over which unrecognized compensation cost is expected to be recognized			1 year 4 months 24 days
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	8,716	6,771	$ 24,359	19,374
Weighted average period over which unrecognized compensation cost is expected to be recognized			2 years 6 months
Vesting period			4 years
Unrecognized compensation cost related to non-option awards	38,800		$ 38,800
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,969	1,388	$ 6,291	3,020
Weighted average period over which unrecognized compensation cost is expected to be recognized			1 year 10 months 24 days
Vesting period			3 years
Unrecognized compensation cost related to non-option awards	8,500		$ 8,500
Performance components \| component			2
Performance Share Units - First Component
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period over which awards expire			3 years
Performance Share Units - Second Component
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period over which awards expire			3 years
Number of tranches \| tranche			3
Performance cycle period of each tranche			1 year
Contract Drilling Services Operating Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,400	1,900	$ 7,600	5,400
Selling, General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 8,700	$ 6,900	$ 24,500	$ 20,100
2016 Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares) \| shares			0
2016 Plan \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares) \| shares			727,009
2016 Plan \| Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares) \| shares			258,857
2020 Plan \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares) \| shares			54,118