Significant Agreements (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	Jun. 30, 2014 Collaborative Arrangement	May 31, 2014 Collaborative Arrangement Roche	Jun. 30, 2014 Collaborative Arrangement Roche	Jun. 30, 2014 Collaborative Arrangement Roche	Jun. 30, 2014 Research Reimbursement Roche	Jun. 30, 2014 Research Reimbursement Roche	Jun. 30, 2014 Development Costs Reimbursement Roche	Jun. 30, 2014 Development Costs Reimbursement Roche	Feb. 28, 2014 License Roche	Jun. 30, 2014 Scenario, Previously Reported [Member] Collaborative Arrangement Roche	Jun. 30, 2014 Scenario, Adjustment [Member] Collaborative Arrangement Roche
License Agreement [Line Items]
Upfront payment pursuant to License Agreement									$ 30.0
Clinical milestone received		15.0
Collaboration service revenue recognized for research services					0.4	0.7
Cost Sharing payments made recognized as R&D expenses			0.4	0.5
Potential payment upon achievement of development, regulatory and various first commercial sales milestones				380.0
Potential payment for achievement of non U.S.commercial sales milestones				175.0
Potential alternative commercial sales milestone payment				155.0
Portion of revenue and expenses attributable to company, percentage	30.00%			70.00%
Multiple element consideration, relative sales price method, amount allocable to license										34.7	35.6
Development reimbursement			1.4	3.5
Development reimbursement recognized as collaboration license revenue							1.3	3.1
Development Reimbursement Recognized As Offset To Research And Development Expense							0.2	0.4
Milestone payment recognized as collaboration revenue			13.3
Milestone payment used as offset to R&D expense			$ 1.7