Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 6,888	$ 7,503
Less accumulated depreciation and amortization	(4,044)	(4,580)
Property and equipment, net	2,844	2,923
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,794	928
Property and equipment, useful life in years	5 years
Systems Hardware
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,623	3,320
Property and equipment, useful life in years	5 years
Office Computers
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,285	1,777
Property and equipment, useful life in years	3 years
Computer and System Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,186	$ 1,478
Property and equipment, useful life in years	3 years