Other Current Assets and Other Long-Term Assets - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 5,884	$ 5,672
Deposits and other receivables	1,613	2,119
Interest receivable	1,959	1,566
Other current assets	9,456	9,357
Deposits paid for research and development	5,600	5,100
Long-term operating right-of-use asset	400	600
Security deposit for lease	$ 300	$ 300