Leases - Weighted Average Remaining Lease Term, and Weighted Average Discount Rates Related to Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Leases [Abstract]
Right-of-use assets from operating leases	$ 12,932	$ 18,483
Operating lease liabilities	4,118	4,494
Operating lease liabilities - non-current	12,694	15,959
Total operating lease liabilities	$ 16,812	$ 20,453
Weighted average remaining lease term	4 years 4 months 24 days	4 years 7 months 6 days
Weighted average discount rate	5.50%	5.70%