CONSOLIDATED AND COMBINED STATEMENT OF EQUITY AND CHANGES IN PARENT COMPANY EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in-Capital	Accumulated Deficit	Net Parent Investment	Accumulated Other Comprehensive Income (Loss)
Balance at Sep. 30, 2017	$ 997,179				$ 1,019,792	$ (22,613)
Balance (ASU 2016-16) at Sep. 30, 2017	(1,510)				(1,510)
Net (loss) income	5,881				5,881
Other comprehensive income (loss)	(1,344)					(1,344)
Net transfer to Parent	(6,887)				(6,887)
Balance at Sep. 30, 2018	993,319				1,017,276	(23,957)
Balance (ASC 606) at Sep. 30, 2018	6,974				6,974
Net (loss) income	100,268				100,268
Other comprehensive income (loss)	(5,042)					(5,042)
Net transfer to Parent	(27,391)				(27,391)
Balance at Sep. 30, 2019	1,068,128				1,097,127	(28,999)
Net (loss) income	(20,631)			$ (20,631)
Other comprehensive income (loss)	16,982					16,982
Distribution to Parent	(152,978)				(152,978)
Net (decrease) increase in net parent investment	9,630				(6,098)	15,728
Reclassification of net parent investment in Cerence			$ 938,051		$ (938,051)
Issuance of common stock at separation		$ 364	(364)
Issuance of common stock at separation, (in shares)		36,391
Issuance of common stock under employee stock plans	1,318	$ 7	1,311
Issuance of common stock under employee stock plans, (in shares)		706
Stock withheld to cover tax withholdings requirements upon restricted stock vesting	(9,369)	$ (2)	(9,367)
Stock withheld to cover tax withholdings requirements upon restricted stock vesting, (in shares)		(255)
Convertible Senior Notes conversion feature	14,371		14,371
Stock-based compensation	30,305		30,305
Balance at Sep. 30, 2020	$ 957,756	$ 369	$ 974,307	$ (20,631)		$ 3,711
Balance (in shares) at Sep. 30, 2020		36,842