Development and License Agreements - Summary of Prepaid R&D Asset and Manufacturing Efficiency Asset (Detail) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Other current assets
Deferred Costs Capitalized Prepaid And Other Assets [Line Items]
Prepaid R&D asset - current	[1]	$ 33	$ 114
Other assets
Deferred Costs Capitalized Prepaid And Other Assets [Line Items]
Prepaid R&D asset - current	[2]	2,176	2,162
Manufacturing efficiency asset	[2]	$ 1,656	$ 1,839

[1] Included in “Other current assets” in the Company's consolidated balance sheets.

[2] Included in “Other assets” in the Company's consolidated balance sheets