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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, RISKS AND UNCERTAINTIES - International Land Drilling Risks (Details) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) greographical_area | Jun. 30, 2018 USD ($)
Unusual Risk or Uncertainty [Line Items] |  |  |  |
Cumulative inflation rate before a country is considered highly inflationary (as a percent) |  |  | 100.00% |
Foreign currency gain (loss) | $ | $ 0.1 | $ (1.1) | $ (4.6) | $ (2.5)
Minimum |  |  |  |
Unusual Risk or Uncertainty [Line Items] |  |  |  |
Number of geographical areas operating in (more than) | greographical_area |  |  | 1 |

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- Definition Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30700-110894 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894 + Details
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