Statements of Consolidated Comprehensive Income Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 44,035	$ 53,667	$ 65,827	$ 66,560
Foreign currency translation adjustment	173	(439)	(2,891)	(317)
Amortization of net actuarial loss included in net periodic benefit expense or income, net of deferred tax of $1,285 and $794, respectively	2,080	1,182	4,149	2,425
Amortization of prior service credit included in net periodic benefit expense or income, net of deferred tax of $80 and $122, respectively	(129)	(190)	(257)	(379)
Other Comprehensive Income, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	1,951	992	3,892	2,046
Total Other Comprehensive Income (Loss)	2,124	553	1,001	1,729
Comprehensive Income	$ 46,159	$ 54,220	$ 66,828	$ 68,289