Statement of Comprehensive Income Statement (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 12,893	$ 14,005
Foreign currency transaction adjustment	122	440
Net actuarial loss included in net periodic benefit expense or income, net of deferred tax of $794 and $1,922, respectively	1,243	3,007
Amortization of prior service cost or credit included in net periodic benefit expense or income, net of deferred tax of $122 and $61, respectively	(189)	95
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	1,054	3,102
Total other comprehensive income	1,176	3,542
Comprehensive income	$ 14,069	$ 17,547