Other Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Income and Expenses [Abstract]
Interest income (expense)	$ 138	$ (73)	$ 342	$ 65
Other nonoperating income	8	33	238	299
Insurance policy (expense) income	(48)	(58)	(146)	70
Other nonoperating expense	(3)	(4)	(10)	(10)
Other income (expense), net	$ 95	$ (102)	$ 424	$ 424