Kolltan Acquisition - Allocations of Assets and Liabilities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Nov. 29, 2016
Summary of fair values of assets acquired and liabilities assumed at acquisition date
Goodwill			$ 90,976	$ 90,976
Kolltan
Kolltan Acquisition
Goodwill expected to be deductible for income tax purposes					$ 0
Summary of fair values of assets acquired and liabilities assumed at acquisition date
Cash and cash equivalents					8,160
Other current and long-term assets					799
Property and equipment, net					2,072
In-process research and development (IPR&D)					61,690
Goodwill					82,011
Deferred tax liabilities, net					(23,393)
Other assumed liabilities					(9,974)
Total					$ 121,365
Pro Forma Financial Information
Net loss	$ 39,500	$ 84,800
Basic and Diluted Net Loss Per Common Share	$ (0.34)	$ (0.73)