Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 123,913	$ 104,291
Reserves and accruals	4,281	2,922
Depreciation and amortization	712	548
Tax credit carryforwards	12,584	11,098
Stock-based compensation	7,057	7,185
Total deferred tax assets	148,547	126,044
Valuation allowance on deferred tax assets	(146,285)	(124,137)
Total deferred tax assets, net of valuation allowance	2,262	1,907
Deferred Tax Liabilities, Gross [Abstract]
Fixed asset and intangibles	(22,000)	(25,565)
Total deferred tax liabilities	(22,000)	(25,565)
Net deferred tax liability	$ (19,738)	$ (23,658)