Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 77,175	$ 78,657	$ 162,137	$ 121,987
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	1,958	1,557	5,717	5,259
Change in fair value of derivatives	152	(587)	3,013	(965)
Foreign currency translation	11,553	15,728	(5,036)	6,208
Other comprehensive income	13,663	16,698	3,694	10,502
Comprehensive income	$ 90,838	$ 95,355	$ 165,831	$ 132,489