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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Drilling revenues (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
DRILLING REVENUES |  |  |
Reimbursements received | $ 179.9 | $ 125.9 | $ 302.2
Early termination revenue | $ 29.4 | $ 219.0 | $ 222.3

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- Definition Revenue related to early termination of contract. + References No definition available. + Details
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- Definition Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 45 -Section 45 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=68075638&loc=d3e60722-111653 + Details
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