Supplemental Operating Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Nonoperating Income (Expense) [Abstract]
Other nonoperating expense, net	$ (3,989)	$ (5,744)	$ (3,050)
Foreign currency gains (losses)	$ 113	$ (854)	$ (235)