Income Taxes - Summary of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	[1]	$ 27,090	$ 34,287
Credit carryforwards		7,478	6,492
Capitalized research and development		3,665	6,992
Deferred rent		1,189	1,825
Allowances		1,466	767
Deferred compensation		218	1,209
Deferred revenue		108	331
Stock compensation		525	220
Deferred tax assets		41,739	52,123
Less: valuation allowance		(41,130)	(50,959)
Net deferred tax assets		609	1,164
Deferred tax liability
Goodwill		(532)	(766)
Depreciation and amortization		(609)	(1,164)
Deferred tax liabilities		(1,141)	(1,930)
Net deferred tax liability		$ (532)	$ (766)

[1] During the prior year, we recorded an increase to the NOL and increase to the valuation allowance of $727,000 as a result of the adoption of ASU 2016-09, “Improvements to Employee Share-Based Payment Accounting.”