Inventory - Components of Inventory (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Raw materials	$ 2,724	$ 2,487
Work in process	2,977	2,781
Inventory	9,054	9,502	[1]
Arena GmbH
Inventory [Line Items]
Finished goods	0	165
Eisai
Inventory [Line Items]
Finished goods	2,720	3,309
Ildong
Inventory [Line Items]
Finished goods	$ 633	$ 760

[1] The balance sheet data at December 31, 2015, has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by US generally accepted accounting principles for complete financial statements.