Commitments and Contingencies	3 Months Ended
Mar. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Purchase Commitments The Company conducts product research and development programs through a combination of internal and collaborative programs that include, among others, arrangements with universities, contract research organizations and clinical research sites. The Company has contractual arrangements with these organizations; however, these contracts are generally cancelable on 30 days’ notice and the obligations under these contracts are largely based on services performed. Facility Leases On June 29, 2012, the Company entered into a 66-month lease for approximately 12,000 square feet of office and laboratory space in South San Francisco with annual payments of approximately $0.5 million. In connection with this lease agreement, the Company also entered into a shared facilities and services agreement with Global Blood Therapeutics, Inc. (“GBT”), a co-tenant in the office building (See Note 10). In October 2014, the Company entered into a lease assignment agreement with the owner of the building and GBT to allow GBT to sublease the Company’s portion of the building beginning in March 2015. For the three months ended March 31, 2016, the Company recorded approximately $0.1 million of sublease income and $0.1 million of sublease expense, which is recorded in interest and other income, net in the consolidated statements of operations and comprehensive loss. On September 15, 2014, the Company entered into a five-year lease for approximately 34,400 square feet of office and laboratory space in South San Francisco. The Company may extend the lease for an additional three year term. The initial annual lease payments are $1.3 million, increasing to $1.6 million in the final year of the agreement. The lease period commenced in January 2015. The Company received a lease abatement for the first three months of the lease term, which is recorded as deferred rent and recognized over the lease term. The Company has provided deposits for letters of credit totaling $0.3 million to secure its obligations under its leases, which have been classified as long-term assets on the Company’s consolidated balance sheet as of March 31, 2016. Rent expense, net was $0.3 million and $0.3 million for the three months ended March 31, 2016, and 2015, respectively. Contingencies From time to time, the Company may have contingent liabilities that arise in the ordinary course of business activities. The Company accrues for such a liability when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There were no contingent liabilities requiring accrual or disclosure as of March 31, 2016, or December 31, 2015. Guarantees and Indemnifications The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to certain of these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third-party with respect to the Company’s technology. The term of these indemnification arrangements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable because it involves claims that may be made against the Company in the future, but have not yet been made. The Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws, and agreements providing for indemnification entered into with its officers and directors. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity. The maximum amount of potential future indemnification of directors and officers is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with its exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

6. Commitments and Contingencies

Purchase Commitments

The Company conducts product research and development programs through a combination of internal and collaborative programs that include, among others, arrangements with universities, contract research organizations and clinical research sites. The Company has contractual arrangements with these organizations; however, these contracts are generally cancelable on 30 days’ notice and the obligations under these contracts are largely based on services performed.

Facility Leases

On June 29, 2012, the Company entered into a 66-month lease for approximately 12,000 square feet of office and laboratory space in South San Francisco with annual payments of approximately $0.5 million. In connection with this lease agreement, the Company also entered into a shared facilities and services agreement with Global Blood Therapeutics, Inc. (“GBT”), a co-tenant in the office building (See Note 10). In October 2014, the Company entered into a lease assignment agreement with the owner of the building and GBT to allow GBT to sublease the Company’s portion of the building beginning in March 2015. For the three months ended March 31, 2016, the Company recorded approximately $0.1 million of sublease income and $0.1 million of sublease expense, which is recorded in interest and other income, net in the consolidated statements of operations and comprehensive loss.

On September 15, 2014, the Company entered into a five-year lease for approximately 34,400 square feet of office and laboratory space in South San Francisco. The Company may extend the lease for an additional three year term. The initial annual lease payments are $1.3 million, increasing to $1.6 million in the final year of the agreement. The lease period commenced in January 2015. The Company received a lease abatement for the first three months of the lease term, which is recorded as deferred rent and recognized over the lease term.

The Company has provided deposits for letters of credit totaling $0.3 million to secure its obligations under its leases, which have been classified as long-term assets on the Company’s consolidated balance sheet as of March 31, 2016.

Rent expense, net was $0.3 million and $0.3 million for the three months ended March 31, 2016, and 2015, respectively.

Contingencies

From time to time, the Company may have contingent liabilities that arise in the ordinary course of business activities. The Company accrues for such a liability when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There were no contingent liabilities requiring accrual or disclosure as of March 31, 2016, or December 31, 2015.

Guarantees and Indemnifications

The Company enters into standard indemnification arrangements in the ordinary course of business.

Pursuant to certain of these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third-party with respect to the Company’s technology. The term of these indemnification arrangements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable because it involves claims that may be made against the Company in the future, but have not yet been made.

The Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws, and agreements providing for indemnification entered into with its officers and directors. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification of directors and officers is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with its exposure and may enable it to recover a portion of any future amounts paid.

The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.