Accrued Expenses and Other Current Liabilities (Severance and Restructuring Accruals) (Narrative) (Details)		1 Months Ended					3 Months Ended	12 Months Ended
	Jun. 07, 2016 USD ($)	Mar. 31, 2018 employee	Mar. 31, 2017 employee	Nov. 30, 2016 employee	May 31, 2016 employee	Dec. 31, 2015 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) employee	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Payables and Accruals [Line Items]
Payments to terminate lease agreement										$ 200,000
Expense - charged to accrual								$ 698,000	$ 1,994,000
Employee Severance
Payables and Accruals [Line Items]
Restructuring costs									400,000
Expense - charged to accrual								512,000	1,994,000
Restructuring- related accruals
Payables and Accruals [Line Items]
Expense - charged to accrual								$ 186,000	0
Satellite Communications Assembly Operations | Employee Severance
Payables and Accruals [Line Items]
Number of positions eliminated | employee				5	30
Restructuring costs									200,000	300,000
Water Fabrication Lab
Payables and Accruals [Line Items]
Number of positions eliminated | employee			14
Water Fabrication Lab | Employee Severance
Payables and Accruals [Line Items]
Number of positions eliminated | employee			72
Restructuring costs									100,000
Workforce Reduction | Employee Severance
Payables and Accruals [Line Items]
Number of positions eliminated | employee			6
Restructuring costs							$ 400,000
New Manufacturing Facility in China | Employee Severance
Payables and Accruals [Line Items]
Number of positions eliminated | employee			265
Restructuring costs									500,000
Ivyland, Pennsylvania Location Closure | Employee Severance
Payables and Accruals [Line Items]
Number of positions eliminated | employee								11
Restructuring costs									$ 300,000
Ivyland, Pennsylvania Location Closure | Restructuring- related accruals
Payables and Accruals [Line Items]
Expense - charged to accrual								$ 200,000
Alignment Towards Chip Devices and Navigation Systems
Payables and Accruals [Line Items]
Number of positions eliminated | employee		21
Alignment Towards Chip Devices and Navigation Systems | Employee Severance
Payables and Accruals [Line Items]
Restructuring costs								$ 400,000
Discontinued Operations, Disposed of by Sale
Payables and Accruals [Line Items]
Payments to terminate lease agreement						$ 200,000				200,000
Gain on lease termination										300,000
Chief Financial Officer
Payables and Accruals [Line Items]
Continuation of base salary, period	448 days
Continuation of benefits, period	16 months
Outplacement services, period	1 year
Outplacement services	$ 15,000
Estimated charge related to separation agreement										$ 400,000