Collaboration Agreements (Details) - USD ($)		1 Months Ended	12 Months Ended
	Mar. 07, 2018	Mar. 31, 2014	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2012	Dec. 31, 2011
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment performance description			the Company recognized the upfront payment as revenue ratably over the two-year period ended March 18, 2016.
Sales Based Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from milestone payments			$ 0
Teva Pharmaceutical [Member] | TV-45070 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from upfront fee					$ 41,000,000
Teva Pharmaceutical [Member] | Subsequent Event [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative development and license agreement termination date	Mar. 07, 2018
Genentech [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from upfront fee		$ 1,500,000
Potential Milestone Payments Receivable		$ 1,500,000				$ 613,000,000
Proceeds from milestone payments			250,000	$ 250,000
Genentech [Member] | Pre-clinical And Clinical Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Milestone Payments Receivable						45,500,000
Genentech [Member] | Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Milestone Payments Receivable						387,500,000
Genentech [Member] | Sales Based Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Milestone Payments Receivable						180,000,000
Genentech [Member] | Pre-clinical Clinical and Regulatory Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from milestone payments			$ 0
Genentech [Member] | GDC-0276 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from upfront fee						$ 10,000,000