Discontinued Operations Income (Loss) Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Apr. 01, 2016	Mar. 31, 2017	Apr. 01, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	$ 2,268	$ 6,768	$ 4,964	$ 14,834
Operating earnings (loss)	(808)	(1,960)	(6,735)	(7,216)
Tax expense (benefit)	(774)	63	(1,365)	(413)
Income (loss) from discontinued operations	(34)	(2,023)	(5,370)	(6,803)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	319	(1,055)	(4,409)	(3,572)
Gain on sale of discontinued operation	1,188		1,188	0
Avionics & Controls
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	2,268	4,479	4,964	10,061
Operating earnings (loss)	752	1,072	(119)	1,969
Tax expense (benefit)	(191)	273	(430)	686
Income (loss) from discontinued operations	943	799	311	1,283
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	54	326	(86)	56
Gain on sale of discontinued operation	1,188		1,188
Sensors & Systems
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	0	0	0	0
Operating earnings (loss)	(2)	(151)	893	(307)
Tax expense (benefit)	0	0	0	0
Income (loss) from discontinued operations	(2)	(151)	893	(307)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	0	0	0	0
Gain on sale of discontinued operation	0		0
Advanced Materials
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	0	2,289	0	4,773
Operating earnings (loss)	(1,269)	(2,874)	(6,616)	(8,867)
Tax expense (benefit)	(482)	(210)	(623)	(1,099)
Income (loss) from discontinued operations	(787)	(2,664)	(5,993)	(7,768)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	265	(1,381)	(4,323)	(3,628)
Gain on sale of discontinued operation	0		0
Other
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	0	0	0	0
Operating earnings (loss)	(289)	(7)	(893)	(11)
Tax expense (benefit)	(101)	0	(312)	0
Income (loss) from discontinued operations	(188)	(7)	(581)	(11)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	0	$ 0	0	$ 0
Gain on sale of discontinued operation	$ 0		$ 0