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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Valuation of long-lived assets (Details) $ in Millions | 12 Months Ended
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Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) item | Sep. 30, 2015 USD ($) item
U.S. Land |  |  |
VALUATION OF LONG-LIVED ASSETS |  |  |
Impairment charge for asset held for sale |  | $ 6.3 |
Land Rigs |  |  |
VALUATION OF LONG-LIVED ASSETS |  |  |
Depreciation catch-up adjustment | $ 2.2 |  |
Land Rigs | International Land |  |  |
VALUATION OF LONG-LIVED ASSETS |  |  |
Impairment charge for asset held for use |  |  | $ 39.2
Number of impaired land rigs | item |  |  | 7
Land Rigs | International Land | Assets held for sale |  |  |
VALUATION OF LONG-LIVED ASSETS |  |  |
Number of impaired land rigs | item |  | 6 |
Land Rigs | International Land | Discounted cash flow |  |  |
VALUATION OF LONG-LIVED ASSETS |  |  |
Fair value of land rigs |  |  | $ 20.6

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- Definition For the asset that is reclassified back to held and use from held-for-sale, the depreciation expense recognized when the asset is reclassified. This represents the difference between the carrying value at the time the decision to reclassify is made and the carrying amount that the asset would have had if it had never been classified as held for sale (including consideration of depreciation expense). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2459-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 35 -Paragraph 44 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=29634951&loc=d3e1756-110224 + Details
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- Definition The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 225 -Section 45 -Paragraph 11 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84241808&loc=d3e92212-112881 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230 + Details
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