Consolidated Statement of Changes in Retained Earnings and Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 602,578
Net income	125,115	$ 26,956	$ 93,862
Pension and post-retirement plan adjustments, net of tax	(17,569)	20,120	1,321
Reclassification from accumulated other comprehensive (loss) into net income	774		3,270
Unrecognized net losses on available-for-sale securities (Note 18)	(572)
Income attributable to noncontrolling interests	(660)	(3,694)	(3,578)
Balance at end of period	639,519	602,578
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	868,675	901,415	858,553
Net income	125,115	26,956	93,862
Income attributable to noncontrolling interests	(965)	(929)	(1,926)
Common dividends	(57,206)	(52,495)	(49,032)
Preferred dividends	(42)	(42)	(42)
Balance at end of period	935,577	868,675	901,415
Accumulated Other Comprehensive (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(171,762)	(230,246)	(208,199)
Foreign currency translation adjustments	(30,103)	41,129	(24,986)
Pension and post-retirement plan adjustments, net of tax	(17,569)	20,120	1,321
Income attributable to noncontrolling interests	305	(2,765)	(1,652)
Balance at end of period	$ (218,927)	(171,762)	$ (230,246)
Accounting Standards Update 2016-16 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of ASU 2016-16 (Note 1)		$ (6,230)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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