Kolltan Acquisition - Allocations of Assets and Liabilities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016	Nov. 29, 2016
Summary of fair values of assets acquired and liabilities assumed
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
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	$ (35,500)	$ (120,400)
Basic and Diluted Net Loss Per Common Share	$ (0.3)	$ (1.02)