Supplemental Balance Sheet Information - Schedule of Other Non-current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other non-current assets
Goodwill	$ 109	$ 109
Prepayment of property and equipment	34,579	16,984
Prepayment of facility capacity expansion activities	23,816	29,778
Prepaid VAT	21,499	10,913
Rental deposits and other	7,691	5,962
Long-term investments (Note 4)	87,428	49,344
Total	$ 175,122	$ 113,090