Segment Information (External Net Sales by Geographical Area) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated net sales	$ 719,359	$ 588,117	$ 548,249	$ 470,148	$ 606,788	$ 548,622	$ 500,381	$ 442,894	$ 2,325,873	$ 2,098,685	$ 2,023,078
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									1,350,708	1,211,902	1,118,833
All Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									138,191	119,806	137,661
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									323,109	305,545	337,356
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									230,834	173,180	200,545
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									$ 283,031	$ 288,252	$ 228,683