Consolidated Statement of Changes in Retained Earnings and Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 639,519
Net income	137,649	$ 125,115	$ 26,956
Pension and post-retirement plan adjustments, net of tax	(5,559)	(17,569)	20,120
(Income) loss attributable to noncontrolling interests	(1,136)	(660)	(3,694)
Balance at end of period	732,573	639,519
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	935,577	868,675	901,415
Net income	137,649	125,115	26,956
(Income) loss attributable to noncontrolling interests	(1,209)	(965)	(929)
Common dividends	(63,481)	(57,206)	(52,495)
Preferred dividends	(42)	(42)	(42)
Cumulative effect of the adoption of ASU 2016-16 (Note 1)	3,772		(6,230)
Balance at end of period	1,012,266	935,577	868,675
Accumulated Other Comprehensive (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(218,927)	(171,762)	(230,246)
Foreign currency translation adjustments	(1,657)	(30,103)	41,129
Pension and post-retirement plan adjustments, net of tax	(5,559)	(17,569)	20,120
Unrecognized net losses on available-for-sale securities (Note 18)	578	(572)
Reclassification of currency translation from accumulated other comprehensive (loss) into net income (Note 5)	15,261	774
(Income) loss attributable to noncontrolling interests	73	305	(2,765)
Cumulative effect of the adoption of ASU 2016-16 (Note 1)	(3,772)
Balance at end of period	(214,003)	(218,927)	(171,762)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	5,637	4,977	3,047
(Income) loss attributable to noncontrolling interests	1,136	660	3,694
Acquisition of noncontrolling interests			(1,764)
Balance at end of period	$ 6,773	$ 5,637	$ 4,977