Restructuring Costs Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 335,000
Percent of employees terminated	50.00%
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	301,000
Asset Impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 34,000