CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (54,376)	$ (59,857)	$ (71,244)
Other comprehensive (loss) income
Unrealized (losses) gains on available-for-sale investments, net of taxes	(823)	560	395
Comprehensive loss	(55,199)	(59,297)	(70,849)
Total comprehensive loss attributable to Cerus Corporation	$ (55,199)	$ (59,297)	$ (70,849)