Income Taxes - Schedule of Operating Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Contributions (expiring through 2023)	$ 45,081
Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	45,081	$ 41,688
Disallowed interest expense (no expiration)	5,018	0
Contributions (expiring through 2023)	524	210
Research tax credits (expiring through 2025)	135	168
State | New Jersey (expiring in 2038)
Operating Loss Carryforwards [Line Items]
Net operating losses	2,976	4,320
State | Other states (expiring through 2038)
Operating Loss Carryforwards [Line Items]
Net operating losses	2,307	1,072
Foreign
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 257	$ 255