Development and License Agreements - Additional Information (Detail) € in Millions	1 Months Ended	3 Months Ended			12 Months Ended
	Jun. 30, 2016 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2017 EUR (€)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 EUR (€)	Mar. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 EUR (€)
Licenses Agreements [Line Items]
Payments made relating to the manufacturing of the products		$ 3,200,000		$ 3,600,000
Amounts due from Fresenius		$ 900,000					$ 300,000
BARDA Agreement
Licenses Agreements [Line Items]
Committed fund receivable	$ 41,600,000
Committed fund receivable	186,200,000
Period of agreement		5 years	5 years
Accounts receivable of billed and unbilled amounts		$ 700,000					1,000,000
Other current assets
Licenses Agreements [Line Items]
Research and development assets		500,000					900,000
Other assets
Licenses Agreements [Line Items]
Research and development assets		2,000,000					2,000,000
Manufacturing efficiency assets		2,000,000					2,100,000
Fresenius
Licenses Agreements [Line Items]
Allocated amount for research and development activities		4,800,000
Manufacturing efficiency activity cost		2,400,000
Cerus Corporation | BARDA Agreement
Licenses Agreements [Line Items]
Co-investment by the company	$ 14,600,000
Manufacturing and Supply Agreement
Licenses Agreements [Line Items]
Accrual for manufacturing of entity products		3,200,000					3,000,000
Manufacturing and Supply Agreement | Fresenius
Licenses Agreements [Line Items]
Payments made based on the successful achievement of production volumes | €					€ 8.6
Accrual for manufacturing and development of entity products		$ 4,900,000				€ 4.6	$ 4,800,000	€ 4.5
Manufacturing and development obligations, discount rate		9.72%	9.72%
Manufacturing and development payments		$ 3,400,000	€ 3.1