Business Segment Information - Geographic Information Net Sales (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net Sales	$ 236,658	$ 199,766	$ 193,949	$ 182,597	$ 231,086	$ 192,223	$ 174,778	$ 173,495	$ 812,970	$ 771,582	$ 685,740
United States
Net Sales									582,972	536,700	503,100
Asia
Net Sales									88,300	94,500	69,800
Europe
Net Sales									82,800	85,000	75,400
Canada
Net Sales									33,200	30,300	22,200
India
Net Sales									11,700	9,400	4,800
Other
Net Sales									$ 14,000	$ 15,700	$ 10,400