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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, RISKS AND UNCERTAINTIES - Narrative (Details) | 3 Months Ended |  |  |  |  |  |
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Dec. 31, 2021 USD ($) geographical_area | Dec. 31, 2020 USD ($) | Sep. 30, 2021 USD ($) | Sep. 29, 2021 USD ($) | Sep. 27, 2021 | Sep. 30, 2020 USD ($) | Dec. 20, 2018 USD ($) | Nov. 13, 2018 USD ($)
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cash, cash equivalents, and short-term investments | $ 441,300,000 |  |  |  |  |  |  |
Restricted cash | 18,500,000 | $ 48,700,000 | $ 19,200,000 |  |  | $ 48,900,000 |  |
Additional cash restricted at the election of management for potential insurance claims | 17,400,000 |  | 17,700,000 |  |  |  |  |
Increase (decrease) in cash and cash equivalents and restricted cash Label Role | (684,057,000) | (114,094,000) |  |  |  |  |  |
Payment for extinguishment of long-term debt | 487,148,000 | 0 |  |  |  |  |  |
Adjustments to casualty insurance accruals | (2,200,000) | 500,000 |  |  |  |  |  |
Casualty insurance expense | 8,800,000 | 2,500,000 |  |  |  |  |  |
Stop-loss program, maximum amount of claim | 50,000 |  |  |  |  |  |  |
Stop-loss medical expenses | $ 3,200,000 | 2,300,000 |  |  |  |  |  |
Cumulative inflation rate before a country is considered highly inflationary (as a percent) | 100.00% |  |  |  |  |  |  |
Aggregate foreign currency gain (loss) | $ (1,000,000) | $ (1,800,000) |  |  |  |  |  |
Operating Revenue | Geographic Concentration Risk | International Locations |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Concentration percentage | 9.30% | 4.40% |  |  |  |  |  |
Argentina |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cash | $ 39,600,000 |  |  |  |  |  |  |
South America | Operating Revenue | Geographic Concentration Risk | International Locations | International Solutions |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Concentration percentage | 77.10% | 18.10% |  |  |  |  |  |
Intercompany Eliminations |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Premium revenues and expenses | $ 13,600,000 | $ 7,100,000 |  |  |  |  |  |
Acquisition of Drilling Technology Companies |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Restricted cash | $ 1,100,000 |  | $ 1,500,000 |  |  |  |  |
Minimum |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Number of geographical areas operating in (more than) | geographical_area | 1 |  |  |  |  |  |  |
2018 Credit Facility |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  |  | $ 750,000,000
Borrowings outstanding | $ 0 |  |  |  |  |  |  |
Available borrowing capacity | 750,000,000 |  |  |  |  |  |  |
2018 Credit Facility | Letters of Credit |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  |  | $ 75,000,000
Unsecured Senior Notes Issued 2025 |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Interest rate |  |  |  |  | 4.65% |  |  |
Face amount of debt |  |  |  |  |  |  | $ 487,100,000 |
Loss on extinguishment of debt | 3,700,000 |  |  |  |  |  |  |
Make-whole premium and accrued interest | $ 56,400,000 |  |  |  |  |  |  |
Unsecured Senior Notes Issued 2031 |  |  |  |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Interest rate |  |  |  | 2.90% |  |  |  |
Face amount of debt |  |  |  | $ 550,000,000 |  |  |  |

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