Other Non-Operating Income (Expense), Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Non-Operating Income (Expense), Net [Abstract]
Interest and dividend income	$ 153	$ 151	$ 296
Equity income (loss) from joint ventures	2,029	976	(822)
Loss on foreign exchange	(276)	(719)	(1,562)
Write off of deferred financing costs	0	(773)	0
Other non-operating income, net	153	145	119
Total other non-operating income (expense), net	$ 2,059	$ (220)	$ (1,969)