Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 31,476	$ 25,433
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	(411)	2,042
Change in fair value of derivatives	815	1,463
Foreign currency translation	(10,248)	(12,044)
Other comprehensive loss	(9,844)	(8,539)
Comprehensive income	$ 21,632	$ 16,894