Segment Information (External Net Sales by Geographical Area) (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
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales	$ 531,264	$ 523,826	$ 720,220	$ 720,355	$ 736,537	$ 752,005	$ 758,844	$ 652,811	$ 2,495,665	$ 2,900,197	$ 2,325,873
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales											1,350,708
Net sales									1,426,454	1,628,064
Germany [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales											230,834
Net sales									233,965	302,084
Europe, excluding Germany [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales											323,109
Net sales									$ 336,971	$ 431,416
Asia [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales											283,031
All Other Countries [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales											$ 138,191