Novartis Collaboration and License Agreement ("the Novartis Agreement")	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Novartis Collaboration and License Agreement ("the Novartis Agreement")	Novartis Collaboration and License Agreement (the "Novartis Agreement")In 2019, we entered into the Novartis Agreement for the development and commercialization of our preclinical product candidate, PLN-1474 and up to three additional integrin research targets. PLN-1474 is an internally discovered small molecule selective inhibitor of integrin αvß1, currently being developed for the treatment of liver fibrosis associated with nonalcoholic steatohepatitis (“NASH”). Pursuant to the agreement, we received an upfront, non-refundable license fee of $50.0 million and were eligible to receive additional payments of $416.0 million contingent upon achievement of specified research, development, regulatory and commercial events and royalties on world-wide net sales thereafter. Additionally, Novartis is funding up to $19.6 million associated with research and development services for PLN-1474 and up to $13.4 million for research and development services on the integrin research targets. To date, we have received $25.0 million in contingent payments and $391.0 million remain eligible for achievement. No contingent payments were recognized during the three and six months ended June 30, 2021 and one contingent payment of $25.0 million was recognized in the first quarter of 2020. Revenues for research and development services for the three and six months ended June 30, 2021 and 2020 were $1.8 million and $4.0 million, and $3.6 million and $32.5 million, respectively.