Other Comprehensive Loss (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive income (loss)	$ 582,219	$ 482,063	$ 365,822	$ 362,016
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive income (loss)	16,137	(5,535)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive income (loss)	(7,474)	(10,396)
Other comprehensive income (loss), tax expense (benefit)	(403)	839
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive income (loss)	2,752	(4,541)
Other comprehensive income (loss), tax expense (benefit)	(135)	(135)
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive income (loss)	$ 11,415	$ (20,472)	$ (13,004)	$ (9,017)