Revenue (Schedule of Disaggregation of Revenue) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Total net sales		$ 581,321	$ 720,220	$ 1,118,940	$ 1,440,575
Aerospace [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		364,706	474,236	686,373	948,161
Aerospace [Member] | Commercial OEM [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		101,907	144,610	177,988	303,276
Aerospace [Member] | Commercial Aftermarket [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		77,579	134,042	143,094	259,970
Aerospace [Member] | Defense OEM [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		135,630	139,901	266,893	280,827
Aerospace [Member] | Defense Aftermarket [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		49,590	55,683	98,398	104,088
Industrial [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		216,615	245,984	432,567	492,414
Industrial [Member] | Reciprocating Engines [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		163,034	163,555	327,956	338,208
Industrial [Member] | Industrial Turbines [Member]
Disaggregation Of Revenue [Line Items]
Total net sales		$ 53,581	59,678	$ 104,611	111,177
Industrial [Member] | Renewables [Member]
Disaggregation Of Revenue [Line Items]
Total net sales	[1]		$ 22,751		$ 43,029

[1] Sales in the renewables market were discontinued as of May 1, 2020 following the closing of the divestiture of the renewable power systems business and other related businesses (as described more fully in Note 10, Sale of businesses, and defined therein as the “disposal group”).