Summary of Significant Accounting Policies - Schedule of Cash as Reported in Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 215,229	$ 138,951	$ 181,568
Restricted cash	3,421	1,062
Total cash balance in consolidated statements of cash flows	218,650	140,013	181,741	$ 188,658
SRX Cardio
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	30	173
Royalty Payments | HealthCare Royalty Partners and its Affiliates (“HCR”)
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	3,375	1,032	0
Security Deposit for Office Lease
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 46	$ 0	$ 0