Collaboration and Other Agreements, Servier (Details)	1 Months Ended	12 Months Ended
	Sep. 30, 2012 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) Milestone
Collaboration and Other Agreements [Line Items]
Deferred revenue included in current liabilities		$ 4,261,000	$ 5,866,000
Deferred revenue included in long-term liabilities		10,045,000	12,631,000
Servier | Servier DART
Collaboration and Other Agreements [Line Items]
Nonrefundable upfront payment	$ 20,000,000
Original period of development	29 months
Expected period of development	75 months
Change in accounting estimate, current year impact				$ 3,700,000
Option exercise fee				$ 15,000,000
Option exercise fee recognition period				82 months
Offset to research and development costs under collaboration arrangement		2,600,000	500,000	$ 1,000,000
Recognized revenue under agreement		3,300,000	3,500,000	$ 16,700,000
Number of milestones achieved | Milestone				2
Milestone payment		0	0	$ 5,000,000
Review period				30 days
Deferred revenue		11,100,000	14,400,000
Deferred revenue included in current liabilities		3,300,000	3,300,000
Deferred revenue included in long-term liabilities		$ 7,800,000	$ 11,100,000
Servier | Maximum | Servier DART
Collaboration and Other Agreements [Line Items]
Potential License Fee	$ 40,000,000
Potential clinical milestone payments under agreement	63,000,000
Potential regulatory milestone payments under agreement	188,000,000
Potential sales milestone payments under agreement	$ 420,000,000