Consolidated Statement of Changes in Retained Earnings and Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 558,165
Net income	14,690	$ 12,073
Pension and post-retirement plan adjustments, net of tax of $1,046, $1,267, $3,132, and $4,161 for the three and nine months ended September 30, 2016 and September 30, 2015	1,984	1,892
Income attributable to noncontrolling interests	349	2
Cumulative effect of the adoption of ASU 2016-16 (Note 2)	(5,915)
Ending Balance	576,341
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	901,415	858,553
Net income	14,690	12,073
Income attributable to noncontrolling interests	(277)	(322)
Common dividends	(12,445)	(11,926)
Preferred dividends	(10)	(10)
Ending Balance	897,458	858,368
Accumulated Other Comprehensive (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(230,246)	(208,199)
Foreign currency translation adjustments	10,744	13,948
Pension and post-retirement plan adjustments, net of tax of $1,046, $1,267, $3,132, and $4,161 for the three and nine months ended September 30, 2016 and September 30, 2015	1,984	1,892
Income attributable to noncontrolling interests	626	(324)
Foreign currency translation adjustments reclassified into earnings		2,103
Ending Balance	$ (216,892)	$ (190,580)