Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Change and ending balances for the various components of other comprehensive income (loss) and for accumulated other comprehensive loss
Foreign Currency Translation Adjustments, Beginning Balance	$ (4,736)	$ (5,389)	$ (3,769)
Foreign Currency Translation Adjustments, Changes	3,193	653	(1,620)
Foreign Currency Translation Adjustments, Ending Balance	(1,543)	(4,736)	(5,389)
Unrecognized Components of Employee Benefit Plans, Beginning Balance	(75,225)	(55,861)	(61,457)
Unrecognized Components of Employee Benefit Plans, Changes	(6,558)	(19,364)	5,596
Unrecognized Components of Employee Benefit Plans, Ending Balance	(81,783)	(75,225)	(55,861)
Unrealized Holding Gains (Losses) on Securities, Beginning Balance	562	577	287
Unrealized Holding Gains (Losses) on Securities, Changes	71	(15)	290
Unrealized Holding Gains (Losses) on Securities, Ending Balance	633	562	577
Derivatives, Beginning Balance	109	1,199	695
Fair value of cash flow hedges	209	(1,090)	504
Derivatives, Ending Balance	318	109	1,199
Accumulated Other Comprehensive Loss, Beginning Balance	(79,290)	(59,474)	(64,244)
Accumulated Other Comprehensive Loss, Changes	(3,085)	(19,816)	4,770
Accumulated Other Comprehensive Loss, Ending Balance	$ (82,375)	$ (79,290)	$ (59,474)