Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 581,321	$ 720,220	$ 1,118,940	$ 1,440,575
Costs and expenses:
Cost of goods sold	434,243	517,514	835,883	1,052,431
Selling, general and administrative expenses	44,329	57,629	100,440	119,674
Research and development costs	27,627	34,661	59,623	71,507
Impairment of assets sold				37,902
Interest expense	8,249	8,756	17,155	17,765
Interest income	(283)	(476)	(778)	(963)
Other (income) expense, net	(11,331)	(5,063)	(19,454)	(26,488)
Total costs and expenses	502,834	613,021	992,869	1,271,828
Earnings before income taxes	78,487	107,199	126,071	168,747
Income tax expense	10,174	15,881	16,188	24,056
Net earnings	$ 68,313	$ 91,318	$ 109,883	$ 144,691
Earnings per share:
Basic earnings per share	$ 1.08	$ 1.47	$ 1.74	$ 2.33
Diluted earnings per share	$ 1.04	$ 1.41	$ 1.68	$ 2.24
Weighted Average Common Shares Outstanding:
Basic	63,278	62,266	63,043	62,128
Diluted	65,654	64,564	65,274	64,622