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Segment Information (Narrative) (Details) - segment | 12 Months Ended
--- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Revenue, Major Customer [Line Items] |  |  |
Number of Reportable Segments | 2 |  |
General Electric [Member] | Sales [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 16.00% | 17.00% | 18.00%
General Electric [Member] | Trade Accounts Receivable [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 10.00% | 14.00% |
U.S. Government Related [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 23.00% | 21.00% | 18.00%
U.S. Government Related [Member] | Trade Accounts Receivable [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 3.00% | 2.00% |
The Boeing Company [Member] | Sales [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 11.00% | 8.00% | 7.00%
Weichai Westport, Inc. [Member] | Trade Accounts Receivable [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Percentage of total attributable to major customer | 14.00% | 3.00% |

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