Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 13,857	$ 14,215
Less accumulated depreciation and amortization		(6,603)	(7,931)
Property and equipment, net		7,254	6,284
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 1,999	1,785
Property and equipment, useful life in years		5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	[1]	$ 4,864	4,074
Property and equipment, useful life in years	[1]	9 years
Systems Hardware
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 533	1,596
Property and equipment, useful life in years		5 years
Office Computers
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 5,794	5,309
Property and equipment, useful life in years		3 years
Computer and System Software
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 667	$ 1,451
Property and equipment, useful life in years		3 years

[1] Lesser of the lease term or the estimated useful lives of the improvements, which may generally be up to 9 years.