Consolidated Statements of Changes in Retained Earnings, Accumulated Other Comprehensive Loss and Noncontrolling Interests - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period		$ 923,741			$ 923,741
Net income	$ 76,410	(150,173)	$ 51,489	$ 35,542	58,583	$ 179,630	$ 21,340
Pension and post-retirement plan adjustments, net of tax					7,683	6,961	58,256
Unrecognized net gains on available-for-sale securities (Note 19)							(4)
(Income) loss attributable to noncontrolling interests					0	0	(448)
Preferred stock dividends					(41)	(41)	(41)
Balance at end of period	966,802		923,741		966,802	923,741
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period		1,158,347		1,050,214	1,158,347	1,050,214	1,103,092
Net income					58,583	179,630	21,788
(Income) loss attributable to noncontrolling interests							(448)
Distributions to noncontrolling interests							(5,632)
Common dividends					(73,447)	(71,456)	(68,545)
Preferred stock dividends					(41)	(41)	(41)
Balance at end of period	1,143,442		1,158,347		1,143,442	1,158,347	1,050,214
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period		(158,717)		(149,140)	(158,717)	(149,140)	(182,397)
Foreign currency translation adjustments					21,682	(19,453)	(25,354)
Pension and post-retirement plan adjustments, net of tax					7,683	6,961	58,256
Unrecognized net gains on available-for-sale securities (Note 19)					2	3
Reclassification of currency translation from accumulated other comprehensive loss into net income (Note 6)					101	2,912	267
(Income) loss attributable to noncontrolling interests							92
Balance at end of period	(129,249)		(158,717)		(129,249)	(158,717)	(149,140)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period		$ 0		$ 0	0	0	7,993
(Income) loss attributable to noncontrolling interests							356
Acquisition of noncontrolling interests in consolidated subsidiaries							(8,349)
Balance at end of period	$ 0		$ 0		$ 0	$ 0	$ 0