Restructuring Restructuring Plan (Details Textual) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($)
Restructuring charges	$ 0	$ 0	$ 0	$ 0	$ 286	$ 0	$ 0	$ 0	$ 0	$ 286
2016 Restructuring Plan [Member]
Number of Positions Eliminated (in employee) | employee									7
Restructuring charges									$ 0	$ 300