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%