CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in-Capital	(Accumulated Deficit) Retained Earnings	Net Parent Investment	Accumulated Other Comprehensive Income (Loss)
Balance at Sep. 30, 2019	$ 1,068,128				$ 1,097,127	$ (28,999)
Net income	(11,283)
Balance at Dec. 31, 2019	926,694	$ 364	$ 945,054	$ (11,283)		(7,441)
Balance (in shares) at Dec. 31, 2019		36,403
Balance at Sep. 30, 2019	1,068,128				1,097,127	(28,999)
Net income	1,529			1,529
Other comprehensive income (loss)	(1,364)					(1,364)
Distribution to Parent	(152,978)				(152,978)
Net (decrease) increase in net parent investment	11,453				(4,275)	15,728
Reclassification of net parent investment in Cerence			939,874		(939,874)
Issuance of common stock at separation		$ 364	(364)
Issuance of common stock at separation, (in shares)		36,391
Issuance of common stock	1	$ 1
Issuance of common stock, (in shares)		111
Stock withheld to cover tax withholdings requirements upon stock vesting	(919)	$ 0	(919)
Stock withheld to cover tax withholdings requirements upon restricted stock vesting, (in shares)		(44)
Stock-based compensation	11,325		11,325
Balance at Mar. 31, 2020	937,175	$ 365	949,916	1,529		(14,635)
Balance (in shares) at Mar. 31, 2020		36,458
Balance at Sep. 30, 2019	1,068,128				$ 1,097,127	(28,999)
Net income	(18,316)
Balance at Sep. 30, 2020	960,071	$ 369	974,307	(18,316)		3,711
Balance (in shares) at Sep. 30, 2020		36,842
Balance at Dec. 31, 2019	926,694	$ 364	945,054	(11,283)		(7,441)
Balance (in shares) at Dec. 31, 2019		36,403
Net income	12,812			12,812
Other comprehensive income (loss)	(7,194)					(7,194)
Issuance of common stock	1	$ 1
Issuance of common stock, (in shares)		90
Stock withheld to cover tax withholdings requirements upon stock vesting	(778)		(778)
Stock withheld to cover tax withholdings requirements upon restricted stock vesting, (in shares)		(35)
Stock-based compensation	5,640		5,640
Balance at Mar. 31, 2020	937,175	$ 365	949,916	1,529		(14,635)
Balance (in shares) at Mar. 31, 2020		36,458
Balance at Sep. 30, 2020	960,071	$ 369	974,307	(18,316)		3,711
Balance (in shares) at Sep. 30, 2020		36,842
Net income	20,941
Balance at Dec. 31, 2020	995,720	$ 378	974,866	2,625		17,851
Balance (in shares) at Dec. 31, 2020		37,685
Balance at Sep. 30, 2020	960,071	$ 369	974,307	(18,316)		3,711
Balance (in shares) at Sep. 30, 2020		36,842
Net income	32,104			32,104
Other comprehensive income (loss)	1,923					1,923
Issuance of common stock	5,045	$ 14	5,031
Issuance of common stock, (in shares)		1,390
Stock withheld to cover tax withholdings requirements upon stock vesting	(32,200)	$ (4)	(32,196)
Stock withheld to cover tax withholdings requirements upon restricted stock vesting, (in shares)		(452)
Stock-based compensation	36,498		36,498
Balance at Mar. 31, 2021	1,003,441	$ 379	983,640	13,788		5,634
Balance (in shares) at Mar. 31, 2021		37,780
Balance at Dec. 31, 2020	995,720	$ 378	974,866	2,625		17,851
Balance (in shares) at Dec. 31, 2020		37,685
Net income	11,163			11,163
Other comprehensive income (loss)	(12,217)					(12,217)
Issuance of common stock	1,382	$ 1	1,381
Issuance of common stock, (in shares)		114
Stock withheld to cover tax withholdings requirements upon stock vesting	(1,942)		(1,942)
Stock withheld to cover tax withholdings requirements upon restricted stock vesting, (in shares)		(19)
Stock-based compensation	9,335		9,335
Balance at Mar. 31, 2021	$ 1,003,441	$ 379	$ 983,640	$ 13,788		$ 5,634
Balance (in shares) at Mar. 31, 2021		37,780