Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets
Allowance for doubtful accounts	$ 1,300	$ 1,676
Inventory	489	447
Equity securities and investments in affiliates	17,510	31,729
Accrued liabilities and long-term debt	3,131	4,168
Stock-based compensation	26,936	8,460
Deferred revenue	61,785	68,056
Research and development tax credits	11,385	10,396
Net operating and capital loss carryforwards	111,453	144,502
Total deferred tax assets	233,989	269,434
Less: Valuation allowance	215,582	256,165	$ 190,174	$ 161,660
Net deferred tax assets	18,407	13,269
Deferred tax liabilities
Property, plant and equipment	237	406
Intangible assets	33,790	29,870
Total deferred tax liabilities	34,027	30,276
Net deferred tax liabilities	$ (15,620)	$ (17,007)