Summary of Significant Accounting Policies - Schedule of Cash as Reported in Condensed Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 196,235	$ 215,229	$ 226,793	$ 138,951
Restricted cash	4,274	3,421
Total cash balance in Condensed Consolidated Statements of Cash Flows	200,555	218,650	228,321	140,013
Security Deposit for Office Leases in Europe
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash for office leases in Europe	54	46	0	0
Royalty Payments | HealthCare Royalty Partners and its Affiliates (“HCR”)
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	4,266	3,375	1,499	1,032
SRX Cardio
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 0	$ 0	$ 29	$ 30