Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total debt, Principal	$ 19,499
Less: debt-current	(6,934)	$ (2,956)
Debt-non-current	12,441	16,848
Cerus Term Loans
Debt Instrument [Line Items]
Total debt, Principal	19,499	20,000
Total debt, Unamortized Discount	(124)	(196)
Total debt	19,375	19,804
Less: debt - current, Principal	(7,013)	(3,050)
Less: debt - current, Unamortized Discount	79	94
Less: debt-current	(6,934)	(2,956)
Debt - non-current, Principal	12,486	16,950
Debt - non-current, Unamortized Discount	(45)	(102)
Debt-non-current	$ 12,441	$ 16,848