Other Income (Expense), Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other Income and Expenses [Abstract]
Interest income	$ 1,139	$ 1,304	$ 6,324	$ 7,615
Other nonoperating income	682	739	3,042	2,494
Insurance policy expense	(417)	(2,386)	(4,663)	(5,932)
Other Nonoperating Expense	0	(61)	(16)	(246)
Other income (expense), net	$ 1,404	$ (404)	$ 4,687	$ 3,931