Commitments and Contingencies	12 Months Ended
Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Strategic Collaborations Under our strategic collaboration agreements, we are committed to perform certain research, development, and manufacturing activities. As part of our PCV Agreement and PCV/SAV Agreement with Merck, we are committed to perform certain research, development and manufacturing activities related to PCV products through an initial Phase 2 clinical trial up to a budgeted amount of $243.0 million as of December 31, 2019 and 2018 (Note 3). Legal Proceedings We are not currently a party to any material legal proceedings. Indemnification Obligations As permitted under Delaware law, we indemnify our officers, directors, and employees for certain events, occurrences while the officer, or director is, or was, serving at our request in such capacity. The term of the indemnification is for the officer’s or director’s lifetime. We have standard indemnification arrangements in its leases for laboratory and office space that require it to indemnify the landlord against any liability for injury, loss, accident, or damage from any claims, actions, proceedings, or costs resulting from certain acts, breaches, violations, or non-performance under our leases. Through December 31, 2019 and 2018, we had not experienced any losses related to these indemnification obligations, and no material claims were outstanding. We do not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established. Purchase Commitments and Purchase Orders As of December 31, 2019, we had $4.5 million of non-cancelable purchase commitments for clinical services which are expected to be paid from 2020 to 2023. In addition to purchase commitments, we have agreements with third parties for various services, including services related to clinical operations and support and contract manufacturing, for which we are not contractually able to terminate for convenience and avoid any and all future obligations to the vendors. Certain agreements provide for termination rights subject to termination fees or wind down costs. Under such agreements, we are contractually obligated to make certain payments to vendors, mainly, to reimburse them for their unrecoverable outlays incurred prior to cancellation. At December 31, 2019, we had cancelable open purchase orders of $105.9 million in total under such agreements for our significant clinical operations and support and contract manufacturing. These amounts represent only our estimate of those items for which we had a contractual commitment to pay at December 31, 2019, assuming we would not cancel these agreements. The actual amounts we pay in the future to the vendors under such agreements may differ from the purchase order amounts. Licenses to Patented Technology On June 26, 2017, we entered into sublicense agreements with Cellscript, LLC and its affiliate, mRNA RiboTherapeutics, Inc. to sublicense certain patent rights. Pursuant to each agreement, we are required to pay certain license fees, annual maintenance fees, minimum royalties on future net sales and milestone payments contingent on achievement of certain development, regulatory and commercial milestones for specified products, on a product-by-product basis. We concluded the assets acquired in connection with the sublicense agreements should be accounted for as an asset acquisition of in-process research and development. Accordingly, all payments to be made that meet the characteristics of research and development expenses with no alternative future use will be expensed in the period in which they are incurred. As such, the sublicense payments were expensed as they incurred. Additionally, the development and regulatory milestone payments, up to $1.5 million for therapeutic and prophylactic products and up to $0.5 million for diagnostic products will be recognized as a cost of the asset acquired upon resolution of the associated contingency and will be capitalized or expensed depending on the nature of the associated asset as of the date of recognition. Conversely, commercial milestone payments, up to $24.0 million for therapeutic and prophylactic products will be accounted for as additional expense of the related product sales in the period in which the corresponding sales occur. In conjunction with the agreements entered in 2017, we recognized expense of $22.0 million and $53.3 million, and paid consideration of $25.0 million and $28.3 million in 2018 and 2017, respectively. In 2019, we paid consideration of $22.0 million, which was previously accrued as of December 31, 2018. Additionally, we have other in-license agreements with third parties which require us to make future development, regulatory and commercial milestone payments for specified products associated with the agreements. The achievement of these milestones has not occurred and such milestone payments are immaterial.

Commitments and Contingencies

Strategic Collaborations

Under our strategic collaboration agreements, we are committed to perform certain research, development, and manufacturing activities. As part of our PCV Agreement and PCV/SAV Agreement with Merck, we are committed to perform certain research, development and manufacturing activities related to PCV products through an initial Phase 2 clinical trial up to a budgeted amount of $243.0 million as of December 31, 2019 and 2018 (Note 3).

Legal Proceedings

We are not currently a party to any material legal proceedings.

Indemnification Obligations

As permitted under Delaware law, we indemnify our officers, directors, and employees for certain events, occurrences while the officer, or director is, or was, serving at our request in such capacity. The term of the indemnification is for the officer’s or director’s lifetime.

We have standard indemnification arrangements in its leases for laboratory and office space that require it to indemnify the landlord against any liability for injury, loss, accident, or damage from any claims, actions, proceedings, or costs resulting from certain acts, breaches, violations, or non-performance under our leases.

Through December 31, 2019 and 2018, we had not experienced any losses related to these indemnification obligations, and no material claims were outstanding. We do not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.

Purchase Commitments and Purchase Orders

As of December 31, 2019, we had $4.5 million of non-cancelable purchase commitments for clinical services which are expected to be paid from 2020 to 2023.

In addition to purchase commitments, we have agreements with third parties for various services, including services related to clinical operations and support and contract manufacturing, for which we are not contractually able to terminate for convenience and avoid any and all future obligations to the vendors. Certain agreements provide for termination rights subject to termination fees or wind down costs. Under such agreements, we are contractually obligated to make certain payments to vendors, mainly, to reimburse them for their unrecoverable outlays incurred prior to cancellation. At December 31, 2019, we had cancelable open purchase orders of $105.9 million in total under such agreements for our significant clinical operations and support and contract manufacturing. These amounts represent only our estimate of those items for which we had a contractual commitment to pay at December 31, 2019, assuming we would not cancel these agreements. The actual amounts we pay in the future to the vendors under such agreements may differ from the purchase order amounts.

Licenses to Patented Technology

On June 26, 2017, we entered into sublicense agreements with Cellscript, LLC and its affiliate, mRNA RiboTherapeutics, Inc. to sublicense certain patent rights. Pursuant to each agreement, we are required to pay certain license fees, annual maintenance fees, minimum royalties on future net sales and milestone payments contingent on achievement of certain development, regulatory and commercial milestones for specified products, on a product-by-product basis. We concluded the assets acquired in connection with the sublicense agreements should be accounted for as an asset acquisition of in-process research and development. Accordingly, all payments to be made that meet the characteristics of research and development expenses with no alternative future use will be expensed in the period in which they are incurred. As such, the sublicense payments were expensed as they incurred. Additionally, the development and regulatory milestone payments, up to $1.5 million for therapeutic and prophylactic products and up to $0.5 million for diagnostic products will be recognized as a cost of the asset acquired upon resolution of the associated contingency and will be capitalized or expensed depending on the nature of the associated asset as of the date of recognition. Conversely, commercial milestone payments, up to $24.0 million for therapeutic and prophylactic products will be accounted for as additional expense of the related product sales in the period in which the corresponding sales occur. In conjunction with the agreements entered in 2017, we recognized expense of $22.0 million and $53.3 million, and paid consideration of $25.0 million and $28.3 million in 2018 and 2017, respectively. In 2019, we paid consideration of $22.0 million, which was previously accrued as of December 31, 2018.

Additionally, we have other in-license agreements with third parties which require us to make future development, regulatory and commercial milestone payments for specified products associated with the agreements. The achievement of these milestones has not occurred and such milestone payments are immaterial.