Consolidated Statement of Changes in Retained Earnings and Accumulated Other Comprehensive Loss (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 572,347
Net income	87,927	88,049	91,761
Pension and post-retirement plan adjustments, net of tax ($26,840, $30,849 and $11,364, )	(48,490)	54,951	(28,018)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1,176)	(1,331)	840
Ending Balance	538,633	572,347
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	792,206	747,953	708,306
Net income	87,927	88,049	91,761
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	579	198	(1,124)
Common dividends	(45,544)	(43,952)	(50,948)
Preferred dividends	(42)	(42)	(42)
Ending Balance	835,126	792,206	747,953
Accumulated Other Comprehensive (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(78,269)	(127,072)	(103,184)
Foreign currency translation adjustments	(40,568)	(7,281)	3,846
Pension and post-retirement plan adjustments, net of tax ($26,840, $30,849 and $11,364, )	(48,490)	54,951	(28,018)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	597	1,133	284
Ending Balance	$ (166,730)	$ (78,269)	$ (127,072)