CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (26,267)	$ 16,662	$ (15,006)	$ 45,341
Other comprehensive income (loss):
Foreign currency translation adjustment	4,850	6,909	14,985	(4,205)
Cerence Spin-off	0	0	0	(12,331)
Pension adjustments	36	0	(364)	2,007
Unrealized (loss) gain on marketable securities	(8)	486	(38)	(42)
Total other comprehensive income, net	4,878	7,395	14,583	10,091
Comprehensive (loss) income	$ (21,389)	$ 24,057	$ (423)	$ 55,432