Summary of Revenues Earned in Connection with EUSA Agreement under ASC 606 (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	$ 1,611	$ 1,026
Partnership Royalties
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	157	46
EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and Licensing Revenue	1,600	1,000
Revenues	1,611	1,026
ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	1,611	1,026
ASC 606 | EUSA | Collaboration and Licensing Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	1,454	980
ASC 606 | EUSA | Partnership Royalties
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	$ 157	46
Upfront Payment | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2015-12
Collaboration and Licensing Revenue	$ 99	99
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	$ 723
Milestone - German Reimbursement Approval | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2018-11
Collaboration and Licensing Revenue	$ 79
Milestone - Spanish Reimbursement Approval | ASC 606 | EUSA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date Achieved	2019-02
Collaboration and Licensing Revenue	$ 1,039