Other Income, Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Other Income (Expense), Net [Abstract]
Other income, net	$ 728	$ 979	$ 4,465	$ 5,745
Interest Income [Member]
Other Income (Expense), Net [Abstract]
Other income, net	881	1,481	6,503	6,254
Other Nonoperating Income [Member]
Other Income (Expense), Net [Abstract]
Other income, net	1,157	901	2,079	1,784
Insurance Policy Expense [Member]
Other Income (Expense), Net [Abstract]
Other income, net	(1,061)	(1,215)	(3,860)	(2,086)
Other Nonoperating Expense [Member]
Other Income (Expense), Net [Abstract]
Other income, net	$ (249)	$ (188)	$ (257)	$ (207)