Licensing Agreements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Mars, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential license agreement fee			$ 24.2
Additional potential payments based on sale of first licensed product			95.0
Mars, Inc. | Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Initial license fee		$ 0.2	$ 0.3
High Point Pharmaceuticals L L C And Trans Tech Pharma L L C | Trans Tech License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential license agreement fee	$ 30.5
Additional potential payments based on sale of first licensed product	77.0
High Point Pharmaceuticals L L C And Trans Tech Pharma L L C | Research and Development | Trans Tech License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Initial license fee	$ 0.6	$ 0.6