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	$ 296	$ 400	$ 488	$ 579
Other Nonoperating Income	1	0	0	16
Insurance policy expense	(12)	(32)	(36)	(32)
Other nonoperating expense	0	(231)	0	0
Other income, net	$ 285	$ 137	$ 452	$ 563