Licenses Acquired - Summary Of Research and Development Arrangement Contract (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	$ 83	$ 7,439
Mustang Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	0	2,260
Checkpoint Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	0	2,000
Coronado SO Co, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	0	1,179
Helocyte [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	83	0
Avenue Therapeutics, Inc. [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	$ 0	$ 2,000