Roche License Agreement (Details) - Roche [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended
	May. 31, 2014	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Collaborative Arrangement [Member]
License Agreement [Line Items]
Cost sharing payments recognized as research and development expense		$ 0.8	$ 0.5		$ 2.2	$ 1.0
Multiple element consideration, relative sales price method, amt allocable to license					35.6
Development reimbursement		1.2	1.0		4.2	4.5
Milestone payment received, clinical milestone	$ 15.0
Milestone payment recognized as Collaboration Revenue						13.3
Milestone payment used to offset research and development expense						1.7
Research Reimbursement [Member]
License Agreement [Line Items]
Collaboration service revenue, research services		0.4	0.4		1.1	1.1
Development Costs Reimbursement [Member]
License Agreement [Line Items]
Development reimbursement recognized as collaboration license revenue		0.0	0.9		0.2	4.0
Development reimbursement recognized as offset to research and development expense		$ 1.2	$ 0.1		$ 4.0	$ 0.5
License [Member]
License Agreement [Line Items]
Upfront payment pursuant to license agreement				$ 30.0