Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents, marketable securities and long term investments	$ 175,800
Operating lease liabilities		$ 7,000
Operating lease, right-of-use asset	$ 8,618	$ 6,600
ZILRETTA [Member]
Summary Of Significant Accounting Policies [Line Items]
Product return, period prior to expiration	3 months
Product return, period after expiration	3 months
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Trade Payment Term	1 year