Income Tax (Narrative) (Details) - USD ($)		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 21, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense		$ 0	$ 0	$ 0
Net losses		14,345,000	85,482,000	2,231,000
Estimated tax effect of claimed deductions			2,200,000
Tax payable	$ 0	0
Provisional income tax expense due to Tax Act	18,800,000
Deferred tax assets, valuation allowance	37,751,000	37,751,000	53,603,000		$ 56,600,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	82,100,000	82,100,000	69,700,000	50,600,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 81,300,000	$ 81,300,000	$ 68,900,000	$ 49,800,000