Business Segment Information - Net Sales And Earnings Before Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net Sales	$ 208,030	$ 172,665	$ 180,492	$ 171,728	$ 213,177	$ 178,259	$ 171,243	$ 163,365	$ 732,915	$ 726,044	$ 683,650
Consolidated EBIT									46,500	106,000	89,900
Less: interest expense									(6,730)	(8,092)	(8,798)
Earnings before income taxes									39,743	97,877	81,091
Corporate
Segment Reporting Information [Line Items]
Consolidated EBIT									(78,300)	(41,900)	(35,800)
Aerospace & Defense
Segment Reporting Information [Line Items]
Net Sales									354,320	325,700	286,800
Consolidated EBIT									73,200	70,100	58,700
USG
Segment Reporting Information [Line Items]
Net Sales									191,703	211,900	214,000
Consolidated EBIT									24,400	52,200	43,200
Test
Segment Reporting Information [Line Items]
Net Sales									186,892	188,400	182,900
Consolidated EBIT									$ 27,200	$ 25,600	$ 23,800