Summary of Revenues Earned in Connection with EUSA Agreement under ASC 606 (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	$ 1,920	$ 784
Partnership Royalties
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	361	291
ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	854	784
ASC 606 | EUSA | Collaboration and Licensing Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	493	493
ASC 606 | EUSA | Partnership Royalties
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	$ 361	291
Upfront Payment | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2015-12
Collaboration and Licensing Revenue	$ 98	98
R&D Payment - EMA Approval in RCC | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2017-08
Collaboration and Licensing Revenue	$ 158	158
Milestone - UK Reimbursement Approval | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2018-02
Collaboration and Licensing Revenue	$ 79	79
Milestone - German Reimbursement Approval | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2018-11
Collaboration and Licensing Revenue	$ 79	79
Milestone - Spanish Reimbursement Approval | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2019-02
Collaboration and Licensing Revenue	$ 79	$ 79