Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) ft² item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Lease Obligations
Rent expense	$ 5,700	$ 4,100	$ 3,700
Non-cancelable commitments under operating leases
2017	5,206
2018	5,946
2019	6,734
2020	7,063
2021	4,817
2022 and thereafter	5,117
Total minimum payments	$ 34,883
Leased laboratory and office space located in Redwood City, California
Lease Obligations
Area leased under non-cancelable operating lease agreement (in square feet) | ft²	180,700
Number of non-cancelable operating leases | item	5
Period of time for which entity has an option to extend lease term	5 years
Allowance for certain tenant improvements	$ 2,300
Leased office space located in Geneva, Switzerland
Lease Obligations
Area leased under non-cancelable operating lease agreement (in square feet) | ft²	7,500