Commitments and contingencies - Narrative (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Sep. 30, 2020 |
Feb. 29, 2020 |
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| Commitments and Contingencies Disclosure [Abstract] | ||
| Performance bond commitments | $ 36.5 | |
| Percentage of employees covered by collective bargaining agreements | 6.00% | |
| Loss contingency, maximum potential loss | $ 31.0 | |
| Loss contingency, disallowed amount | $ 19.0 | $ 12.0 |
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- Definition Loss Contingency, Disallowed Amount No definition available.
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- Definition Loss Contingency, Maximum Potential Loss No definition available.
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- Definition The percentage of employees covered by collective bargaining agreements as of the balance sheet date when it serves as a benchmark in a concentration of risk calculation. No definition available.
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- References No definition available.
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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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