Income Taxes - Schedule of NOL Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Federal and state research and development tax credit and other credit carryforwards	$ 65,900	$ 41,500
Domestic country
Operating Loss Carryforwards [Line Items]
NOL carryforwards	99,200	16,500
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
NOL carryforwards	89,500	11,400
Foreign country
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 0	$ 0