Statement of Comprehensive Income Statement (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 53,667	$ 42,897	$ 66,560	$ 56,902
Foreign currency transaction adjustment	(439)	(182)	(317)	258
Net actuarial loss included in net periodic benefit expense or income, net of deferred tax of $756, $1,859, $1,550 and $3,781, respectively	1,182	2,907	2,425	5,914
Amortization of prior service cost or credit included in net periodic benefit expense or income, net of deferred tax of $120, $61, $242 and $122, respectively	(190)	95	(379)	190
Other Comprehensive Income, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	992	3,002	2,046	6,104
Total other comprehensive income	553	2,820	1,729	6,362
Comprehensive income	$ 54,220	$ 45,717	$ 68,289	$ 63,264