Other Income, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income and Expenses [Abstract]
Interest income	$ 1,860	$ 753	$ 1,470
Other nonoperating income	2,241	2,408	3,601
Insurance Policy Expense (Income), Net	(281)	(197)	(806)
Other Nonoperating Expense	(3)	0	0
Other income, net	$ 3,817	$ 2,964	$ 4,265