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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SALES TAX ACCOUNTING (Details) - USD ($) $ in Millions | 1 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2016 | Sep. 30, 2017 | Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Accounting Policies [Abstract] |  |  |  |  |
Sales tax |  |  | $ 39.4 | $ 31.0 | $ 44.1
Sales tax, percentage | 7.00% | 6.875% |  |  |

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- Definition Sales Tax, Percentage + References No definition available. + Details
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- References No definition available. + Details
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