Discontinued Operations Income (Loss) Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	$ 270	$ 4,033	$ 5,234	$ 18,867
Operating earnings (loss)	(1,195)	(7,414)	(7,930)	(14,630)
Tax expense (benefit)	(380)	1,276	(1,745)	863
Income (loss) from discontinued operations	(815)	(8,690)	(6,185)	(15,493)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	872	(4,323)	(3,537)	(7,895)
Gain (loss) on sale of discontinued operations	(395)		793	0
Avionics & Controls
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	0	3,577	4,964	13,638
Operating earnings (loss)	(594)	(1,184)	(713)	785
Tax expense (benefit)	(62)	570	(492)	1,256
Income (loss) from discontinued operations	(532)	(1,754)	(221)	(471)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	163	(2,411)	77	(2,355)
Gain (loss) on sale of discontinued operations	(395)		793
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)	0	(71)	893	(378)
Tax expense (benefit)	0	(83)	0	(83)
Income (loss) from discontinued operations	0	12	893	(295)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	0	0	0	0
Gain (loss) on sale of discontinued operations	0		0
Advanced Materials
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Sales	270	456	270	5,229
Operating earnings (loss)	(598)	(5,908)	(7,214)	(14,775)
Tax expense (benefit)	(318)	876	(941)	(223)
Income (loss) from discontinued operations	(280)	(6,784)	(6,273)	(14,552)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	709	(1,912)	(3,614)	(5,540)
Gain (loss) on sale of discontinued operations	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)	(3)	(251)	(896)	(262)
Tax expense (benefit)	0	(87)	(312)	(87)
Income (loss) from discontinued operations	(3)	(164)	(584)	(175)
Included in Operating Earnings (Loss):
Gain (loss) on net assets held for sale	0	$ 0	0	$ 0
Gain (loss) on sale of discontinued operations	$ 0		$ 0