Balance Sheet Details (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Restricted Cash
Restricted cash	$ 33,400	$ 27,300
Inventories
Finished products	18,503	14,838
Work in process and inventoried costs under long-term contracts	69,347	73,076
Materials and purchased parts	43,015	39,337
Net inventories	130,865	127,251
Costs incurred outside the scope of work or in advance of a contract award	6,600	5,300
Property, Plant and Equipment
Accumulated depreciation and amortization	(198,953)	(189,394)
Property, plant and equipment - net	165,576	166,301
Deferred Compensation Plan
Deferred compensation	10,100	9,600
Carrying value of Rabbi trust to fund deferred compensation liabilities	7,200	6,800
Land and land improvements
Property, Plant and Equipment
Property, plant and equipment, Gross	7,200	7,423
Buildings and improvements
Property, Plant and Equipment
Property, plant and equipment, Gross	50,166	49,716
Machinery and other equipment
Property, Plant and Equipment
Property, plant and equipment, Gross	145,176	132,962
Software
Property, Plant and Equipment
Property, plant and equipment, Gross	124,753	121,890
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, Gross	23,381	22,295
Construction and internal-use software development in progress
Property, Plant and Equipment
Property, plant and equipment, Gross	$ 13,853	$ 21,409

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