Business Segment Information for Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018		Sep. 29, 2017		Sep. 30, 2016
Segment Reporting Information [Line Items]
Sales	$ 535,294	$ 499,871	$ 517,629	$ 482,045	$ 528,650	$ 504,107	$ 509,131	$ 458,416	$ 2,034,839	[1]	$ 2,000,304	[1]	$ 1,993,453	[1]
Interest income									1,912		527		367
Interest expense									(30,915)		(30,208)		(30,091)
Earnings from Continuing Operations Before Income Taxes									153,576		153,394		136,025
Avionics & Controls
Segment Reporting Information [Line Items]
Sales									861,543		840,777		861,636
Sensors & Systems
Segment Reporting Information [Line Items]
Sales									766,065		724,373		695,712
Advanced Materials
Segment Reporting Information [Line Items]
Sales									407,231		435,154		436,105
Operating Segments
Segment Reporting Information [Line Items]
Segment Earnings									260,395		251,833		237,502
Operating Segments | Avionics & Controls
Segment Reporting Information [Line Items]
Segment Earnings									103,883		91,040		80,521
Operating Segments | Sensors & Systems
Segment Reporting Information [Line Items]
Segment Earnings									85,214		86,902		82,466
Operating Segments | Advanced Materials
Segment Reporting Information [Line Items]
Segment Earnings									71,298		73,891		74,515
Corporate Non Segment
Segment Reporting Information [Line Items]
Corporate expense									$ (77,816)		$ (68,758)		$ (71,753)

[1] Based on country from which the sale originated and the sale was recorded.