Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 28, 2021	Sep. 30, 2024 USD ($) Customer	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Segment Customer	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Description of payment of customer invoice contract				The Company invoices its customers based upon the terms in the contracts, which generally require payment 30 to 60 days from the date of invoice.
Number of major customers representing outstanding accounts receivable | Customer		1		1		3
Shelf life period, platelet kits				12 months
Inventory valuation reserves		$ 700,000		$ 700,000		$ 700,000
Number of reportable segments | Segment				1
Operating expenses		31,799,000	$ 34,538,000	$ 100,022,000	$ 115,326,000
Period of warranty				1 year
Warranty claim liability		0		$ 0		$ 0
Cerus Zhongbaokang Shandong Biomedical Co LTD | China
Summary Of Significant Accounting Policies [Line Items]
Variable interest entity, Purpose of VIE				the Company entered into an Equity Joint Venture Contract with Shandong Zhongbaokang Medical Implements Co., Ltd. (“ZBK”), to establish Cerus Zhongbaokang (Shandong) Biomedical Co., LTD. (the “JV”) for the purpose of developing, obtaining regulatory approval for, and eventual manufacturing and commercialization of the INTERCEPT blood transfusion for platelets and red blood cells in the People’s Republic of China.
Ownership percentage	51.00%
Trade Accounts Receivable | Customer Concentration Risk | Customers
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				35.00%		51.00%
Other Assets
Summary Of Significant Accounting Policies [Line Items]
Cash surrender value of associated life insurance policies		3,000,000		$ 3,000,000		$ 2,600,000
Other Non-current Liabilities
Summary Of Significant Accounting Policies [Line Items]
Liability for deferred compensation		$ 3,100,000		$ 3,100,000		2,800,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Payment of customer invoice contract period				30 days
Estimated useful life of property and equipment		3 years		3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Payment of customer invoice contract period				60 days
Percentage of deferred compensation from base salary				80.00%
Percentage of deferred compensation from variable compensation				100.00%
Shelf lives of inventory				24 months
Estimated useful life of property and equipment		5 years		5 years
Product
Summary Of Significant Accounting Policies [Line Items]
Contract asset		$ 0		$ 0		0
Contract liabilities		$ 700,000		$ 700,000		$ 1,500,000