Financing Agreement with Novo Holdings A/S	12 Months Ended
Dec. 31, 2019
Related Party Transactions [Abstract]
Financing Agreement with Novo Holdings A/S	Financing Agreement with Novo Holdings A/S In May 2013, the Company entered into a Purchase and Sale Agreement (the "Novo Agreement") with Novo Holdings A/S ("Novo" and formerly Novo A/S), pursuant to which the Company obtained financing in three tranches in an aggregate amount equal to $125.0 million in return for the sale to Novo of aggregate royalties of a mid-single digit percentage on worldwide sales of (a) Fovista, (b) certain Fovista-related Products ("Fovista-Related Products"), and (c) certain other antagonists of platelet-derived growth factor ("PDGF"), if any, that the Company initiated development activities for prior to the fifth anniversary of the Novo Agreement (collectively, the "Anti-PDGF Royalty Products"). The Company received the cash payments from Novo in each of May 2013, January 2014 and November 2014. the Company received cash payments of $41.7 million, or $125.0 million in the aggregate. The $125.0 million in aggregate proceeds from the three financing tranches under the Novo Agreement represented the full funding available under the Novo Agreement, and prior to December 31, 2018, was recorded as a royalty purchase liability on the Company's Balance Sheet, in accordance with ASC 730, Research and Development. Because there was a significant related party relationship between the Company and Novo, the Company treated its obligation to make royalty payments under the Novo Agreement as an implicit obligation to repay the funds advanced by Novo. On December 31, 2018, the Company and Novo entered into a letter agreement (the "Novo Termination Agreement"), that terminated the Novo Agreement. As a result of the Novo Termination Agreement, Novo relinquished all rights to receive royalties based on net sales of Anti-PDGF Royalty Products. In exchange, the Company agreed to forbear from any future filing, prosecution, maintenance or enforcement of any intellectual property rights related to Anti-PDGF Royalty Products, and from granting any third party any right or license in any such intellectual property rights or clinical study data generated by or on behalf of the Company, its affiliates, licensees or sublicensees, for the development, manufacture or commercialization of Anti-PDGF Royalty Products or any other antagonists of PDGF. The foregoing restriction does not apply to gene therapies (so long as the Company does not grant any rights or licenses to intellectual property or clinical study data related to Fovista or Fovista-Related Products). The Company further agreed, until December 31, 2028, not to develop, manufacture, seek or obtain regulatory approval for, or commercialize any Anti-PDGF Royalty Products without the prior written consent of Novo. The foregoing restriction does not apply to any gene therapies (so long as the Company does not utilize data related to Fovista or Fovista-Related Products). As a result of the Novo Termination Agreement, the Company has no obligation to repay Novo the $125.0 million through future product royalties or any other development activities. Accordingly, the Company extinguished the $125.0 million royalty purchase liability from its Consolidated Balance Sheet at December 31, 2018 and recognized a related gain of $125.0 million in its Consolidated Statements of Operations for the year ended December 31, 2018. The extinguishment of the royalty purchase liability and the related gain did not impact the Company's cash balance during that period, as the Company had received the proceeds related to the royalty purchase liability in prior periods.

Financing Agreement with Novo Holdings A/S

In May 2013, the Company entered into a Purchase and Sale Agreement (the "Novo Agreement") with Novo Holdings A/S ("Novo" and formerly Novo A/S), pursuant to which the Company obtained financing in three tranches in an aggregate amount equal to $125.0 million in return for the sale to Novo of aggregate royalties of a mid-single digit percentage on worldwide sales of (a) Fovista, (b) certain Fovista-related Products ("Fovista-Related Products"), and (c) certain other antagonists of platelet-derived growth factor ("PDGF"), if any, that the Company initiated development activities for prior to the fifth anniversary of the Novo Agreement (collectively, the "Anti-PDGF Royalty Products"). The Company received the cash payments from Novo in each of May 2013, January 2014 and November 2014. the Company received cash payments of $41.7 million, or $125.0 million in the aggregate.

The $125.0 million in aggregate proceeds from the three financing tranches under the Novo Agreement represented the full funding available under the Novo Agreement, and prior to December 31, 2018, was recorded as a royalty purchase liability on the Company's Balance Sheet, in accordance with ASC 730, Research and Development. Because there was a significant related party relationship between the Company and Novo, the Company treated its obligation to make royalty payments under the Novo Agreement as an implicit obligation to repay the funds advanced by Novo.

On December 31, 2018, the Company and Novo entered into a letter agreement (the "Novo Termination Agreement"), that terminated the Novo Agreement. As a result of the Novo Termination Agreement, Novo relinquished all rights to receive royalties based on net sales of Anti-PDGF Royalty Products. In exchange, the Company agreed to forbear from any future filing, prosecution, maintenance or enforcement of any intellectual property rights related to Anti-PDGF Royalty Products, and from granting any third party any right or license in any such intellectual property rights or clinical study data generated by or on behalf of the Company, its affiliates, licensees or sublicensees, for the development, manufacture or commercialization of Anti-PDGF Royalty Products or any other antagonists of PDGF. The foregoing restriction does not apply to gene therapies (so long as the Company does not grant any rights or licenses to intellectual property or clinical study data related to Fovista or Fovista-Related Products). The Company further agreed, until December 31, 2028, not to develop, manufacture, seek or obtain regulatory approval for, or commercialize any Anti-PDGF Royalty Products without the prior written consent of Novo. The foregoing restriction does not apply to any gene therapies (so long as the Company does not utilize data related to Fovista or Fovista-Related Products).

As a result of the Novo Termination Agreement, the Company has no obligation to repay Novo the $125.0 million through future product royalties or any other development activities. Accordingly, the Company extinguished the $125.0 million royalty purchase liability from its Consolidated Balance Sheet at December 31, 2018 and recognized a related gain of $125.0 million in its Consolidated Statements of Operations for the year ended December 31, 2018. The extinguishment of the royalty purchase liability and the related gain did not impact the Company's cash balance during that period, as the Company had received the proceeds related to the royalty purchase liability in prior periods.