Other Income, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Income and Expenses [Abstract]
Interest income	$ 5,737	$ 7,353	$ 8,343
Other nonoperating income	3,514	4,866	3,025
Insurance policy expense (income), net	(3,851)	(6,923)	(8,292)
Other nonoperating expense	0	0	(104)
Other income, net	$ 5,400	$ 5,296	$ 2,972