Income Taxes (Details Textual) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate						35.00%
Income Tax Expense (Benefit)	$ 0	$ 2,253,000	$ 1,000	$ 2,699,000
Refund Of Tax Credit Description			In addition, the Act repealed the corporate alternative minimum tax (“AMT”) for years beginning after December 31, 2017 and allows companies with existing alternative minimum tax credit (“MTC”) carryforwards as of December 31, 2017 to receive refunds of the credits in tax years after 2017 and before 2022 in an amount equal to 50% (100% in 2021) of the excess MTC over the amount of the credit allowable for the year against regular tax liability.
Tax Credit Carryforward, Limitations on Use			The Act also provides for an indefinite carryforward period for net operating losses generated after 2017 and limits annual utilization to 80% of taxable income. Net operating losses generated prior to 2018 continue to be carried forward for 20 years and have no 80% limitation on utilization.
Income Taxes Receivable, Noncurrent	1,940,000		$ 1,940,000			$ 1,940,000
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		$ 1,400,000
Nj state [Member]
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 1,000		$ 1,000
Scenario, Plan [Member]
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate					21.00%