Development and License Agreements - Additional Information (Detail) € in Millions	1 Months Ended	3 Months Ended			12 Months Ended
	Aug. 31, 2018 EUR (€)	Mar. 31, 2019 USD ($)	Mar. 31, 2019 EUR (€)	Mar. 31, 2018 USD ($)	Dec. 31, 2016 EUR (€)	Mar. 31, 2019 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)
Licenses Agreements [Line Items]
Payments made relating to the manufacturing of the products		$ 7,800,000		$ 5,400,000
BARDA Agreement
Licenses Agreements [Line Items]
Committed fund receivable		103,200,000
Committed fund receivable		$ 201,200,000
Period of agreement		5 years	5 years
Accounts receivable of billed and unbilled amounts		$ 4,200,000					$ 2,300,000
Cerus Corporation | BARDA Agreement
Licenses Agreements [Line Items]
Co-investment by the company		5,000,000
Additional co-investment by the company		9,600,000
Manufacturing and Supply Agreement | Fresenius
Licenses Agreements [Line Items]
Payments made based on the successful achievement of production volumes | €			€ 8.6
Manufacturing and development payments | €					€ 3.1
Remaining amount payable for manufacturing and development | €	€ 5.5
Accrual for manufacturing and development of entity products		$ 6,000,000				€ 5.3	$ 5,900,000	€ 5.2
Manufacturing and Supply Agreement | Fresenius | Measurement Input, Discount Rate
Licenses Agreements [Line Items]
Manufacturing and development obligations, discount rate					0.0972