Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 41,513	$ 45,792	$ 41,453
Operating - current	8,849	9,143	8,443
Operating - noncurrent	33,063	37,199	33,354
Total operating lease liabilities	41,912	46,342	41,797
Property and equipment, gross	3,569	3,569	3,569
Accumulated amortization	(3,340)	(3,112)	(3,036)
Property and equipment, net	229	457	533
Other current liabilities	0	384	771
Total finance lease liabilities	$ 0	$ 384	$ 771