Available-for-Sale Securities and Fair Value Measurements - Summary of the classification of available-for-sale securities in condensed consolidated balance sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total marketable securities	$ 331,755	$ 302,506
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Total marketable securities	67,227	18,461
Short-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Total marketable securities	222,838	244,693
Long-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Total marketable securities	$ 41,690	$ 39,352