License and Research Collaboration Agreements (Details) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014
Deferred Revenue Arrangement [Line Items]
Genentech Upfront Payments			$ 150,000,000
Merck One-Time Milestones					$ 20,000,000
Merck Upfront Payments			$ 30,000,000
Genentech [Member]
Deferred Revenue Arrangement [Line Items]
Genentech Potential Milestones	$ 1,000,000,000			$ 1,000,000,000
Genentech Revenue Recognized	687,000	$ 808,000		2,200,000	14,400,000
Genentech Upfront Payments						$ 150,000,000
Deferred Revenue	642,000			642,000
Reimbursement for direct labor				1,600,000	2,000,000
Alliance manager				502,000	335,000
Participation in JRC				101,000	118,000
Genentech Revenue Allocated to License and Manufacturing Technology Transfer					11,900,000
Merck [Member]
Deferred Revenue Arrangement [Line Items]
Deferred Revenue	51,000			51,000
Merck One-Time Milestones					20,000,000
Merck Upfront Payments						$ 30,000,000
Merck Revenue Recognized	$ 203,000	$ 36,000		$ 764,000	$ 170,000