Other Income, Net of Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Income, Net of Expenses [Abstract]
Interest income	$ 214	$ 175
Gain (loss) on investments	(103)	27
License fee income	194	250
Other	156	60
Total	$ 461	$ 512