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New accounting standards Debt Issuance Costs (Details) - Accounting Standards Update 2015-03 [Member] - Restatement adjustment [Member] - USD ($) | Dec. 31, 2015 | Sep. 30, 2015
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Prepayments and other current assets [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Reclass of debt issuance costs, current | $ 100,000 | $ 100,000
Other [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Reclass of debt issuance costs, non-current | $ 6,000,000 | $ 5,200,000

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