Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of cumulative net gain (loss) by component, net of tax, within other comprehensive income
Foreign currency translation adjustment	$ 4,077	$ 4,947	$ 3,989
Derivative financial instruments
Gross	350	1,450	(1,543)
Deferred tax (benefit)	(1,280)	(895)	(1,942)
Net	1,630	2,345	399
Pension and other retirement plan adjustment
Gross	127,541	105,236	69,441
Deferred tax (benefit)	33,405	25,729	13,437
Net	94,136	79,507	56,004
Total	$ (88,429)	$ (72,215)	$ (51,616)