Commitments and Contingencies - Research and Development and License Agreements and Collaborative Arrangement (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2016 milestone_payment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Number of milestone payments | milestone_payment	2
Research and Development Expense
Loss Contingencies [Line Items]
Service expense		$ 2,535,000	$ 1,362,000	$ 712,000
Boreal
Loss Contingencies [Line Items]
License agreement amount paid		500,000
Boreal | Research and Development Expense
Loss Contingencies [Line Items]
Service expense		475,000
Licensing Agreements | Boreal
Loss Contingencies [Line Items]
Licensing and distribution rights commitment		$ 1,000,000