Other Income (Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income and Expenses [Abstract]
Interest and investment income	$ 72	$ 90	$ 155
Income tax expense	(566)	(295)	(460)
Other non-operating income	126	108	746
Total other income (expense)	$ (368)	$ (97)	$ 441