Commitments and Contingencies - Additional Information (Details) - USD ($)		1 Months Ended			12 Months Ended
		Jun. 30, 2017	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Minimum lease payments	[1]				$ 9,954,000
Rent expense					2,500,000	$ 1,600,000	$ 1,700,000
Accrued Expenses
Loss Contingencies [Line Items]
Deferred rent expense				$ 100,000	500,000	100,000
Former Owner of Vocal
Loss Contingencies [Line Items]
Rent expense					$ 38,000	44,000	$ 50,000
Massachusetts
Loss Contingencies [Line Items]
Minimum lease payments				$ 7,100,000		$ 7,100,000
Operating lease, term of contract				4 years
Florida
Loss Contingencies [Line Items]
Minimum lease payments			$ 1,300,000
Operating lease, term of contract			7 years
China
Loss Contingencies [Line Items]
Operating lease, term of contract		2 years
Increase in future minimum payments		$ 600,000
England
Loss Contingencies [Line Items]
Operating lease, term of contract		4 years
Increase in future minimum payments		$ 200,000

[1] Operating leases include total future minimum rent payments under non-cancelable operating lease agreements.