Discontinued Operations Assets and Liabilities Held for Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Accounts receivable, net		$ 6,681
Inventories		8,468
Prepaid expenses		230
Income tax refundable		71
Other current assets	$ 3,868
Current Assets of Businesses Held for Sale	3,868	15,450
Net property, plant and equipment	5,262	8,237
Intangibles, net		1,856
Deferred income tax benefits		8
Other assets	4,995	1,299
Non-Current Assets of Businesses Held for Sale	10,257	11,400
Accounts payable	385	1,904
Accrued liabilities	86	8,909
Current Liabilities of Businesses Held for Sale	471	10,813
Deferred income tax liabilities	1,365
Other liabilities	320	320
Non-Current Liabilities of Businesses Held for Sale	1,685	320
Net Assets of Businesses Held for Sale	11,969	15,717
Avionics & Controls
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Accounts receivable, net		2,588
Inventories		8,070
Prepaid expenses		127
Income tax refundable		0
Other current assets	0
Current Assets of Businesses Held for Sale	0	10,785
Net property, plant and equipment	5,262	5,368
Intangibles, net		0
Deferred income tax benefits		(392)
Other assets	0	0
Non-Current Assets of Businesses Held for Sale	5,262	4,976
Accounts payable	0	441
Accrued liabilities	0	7,000
Current Liabilities of Businesses Held for Sale	0	7,441
Deferred income tax liabilities	0
Other liabilities	0	0
Non-Current Liabilities of Businesses Held for Sale	0	0
Net Assets of Businesses Held for Sale	5,262	8,320
Sensors & Systems
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Accounts receivable, net		0
Inventories		0
Prepaid expenses		0
Income tax refundable		0
Other current assets	0
Current Assets of Businesses Held for Sale	0	0
Net property, plant and equipment	0	0
Intangibles, net		0
Deferred income tax benefits		0
Other assets	0	0
Non-Current Assets of Businesses Held for Sale	0	0
Accounts payable	0	0
Accrued liabilities	0	0
Current Liabilities of Businesses Held for Sale	0	0
Deferred income tax liabilities	0
Other liabilities	0	0
Non-Current Liabilities of Businesses Held for Sale	0	0
Net Assets of Businesses Held for Sale	0	0
Advanced Materials
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Accounts receivable, net		4,093
Inventories		398
Prepaid expenses		103
Income tax refundable		71
Other current assets	3,868
Current Assets of Businesses Held for Sale	3,868	4,665
Net property, plant and equipment	0	2,869
Intangibles, net		1,856
Deferred income tax benefits		400
Other assets	4,995	1,299
Non-Current Assets of Businesses Held for Sale	4,995	6,424
Accounts payable	385	1,463
Accrued liabilities	86	1,909
Current Liabilities of Businesses Held for Sale	471	3,372
Deferred income tax liabilities	1,365
Other liabilities	320	320
Non-Current Liabilities of Businesses Held for Sale	1,685	320
Net Assets of Businesses Held for Sale	$ 6,707	$ 7,397