Accumulated Other Comprehensive Loss (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Tax benefit (expense) associated with changes in:
Unrecognized employee benefit costs	$ 5,256	$ 12,958	$ (2,219)
Unrealized holding gains (losses) on marketable securities	(80)	15	(144)
Fair value of cash flow hedges	(61)	427	(801)
Tax benefit (expense) associated with reclassification adjustments:
Amortization of unrecognized employee benefit costs	(2,632)	(2,065)	(1,745)
Realized (gains) losses from sale of marketable securities	42	(7)	(12)
Realized losses (gains) from settlement of cash flow hedges	$ (68)	$ 228	$ 503