CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN TOTAL EQUITY (unaudited) - USD ($) $ in Thousands	Total		Common Shares	Capital in Excess of Stated Value	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interests
Beginning Balance at Dec. 31, 2017	$ 1,730,060		$ 7,175	$ 330,157	$ (666,272)	$ 2,036,006	$ 22,994
Beginning balance (shares) at Dec. 31, 2017			99,414,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	74,925					74,055	870
Other comprehensive income/(loss):
Translation gain (loss)	22,982				22,553		429
Defined benefit plan adjustment, net of tax	5,817				5,817
Derivative financial instruments, net of tax	1,047				1,047
Other comprehensive income/(loss)	29,846				29,417		429
Dividends	(39,535)					(39,535)
Issuance of stock awards	479			479
Issuance of stock awards (shares)			227,000
Shares repurchased	(4,088)			(4,088)
Shares repurchased (shares)			(78,000)
Stock-based compensation	3,048			3,048
Ending Balance at Apr. 01, 2018	1,796,456		$ 7,175	329,596	(637,031)	2,072,423	24,293
Ending balance (shares) at Apr. 01, 2018			99,563,000
Beginning Balance at Dec. 31, 2017	$ 1,730,060		$ 7,175	330,157	(666,272)	2,036,006	22,994
Beginning balance (shares) at Dec. 31, 2017			99,414,000
Other comprehensive income/(loss):
Shares repurchased (shares)	0
Ending Balance at Dec. 31, 2018	$ 1,772,278	[1]	$ 7,175	304,709	(740,913)	2,188,115	13,192
Ending balance (shares) at Dec. 31, 2018	99,829,000		99,829,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 73,768					73,663	105
Other comprehensive income/(loss):
Translation gain (loss)	(2,972)				(2,852)		(120)
Defined benefit plan adjustment, net of tax	7,156				7,156
Derivative financial instruments, net of tax	1,864				1,864
Other comprehensive income/(loss)	6,048				6,168		(120)
Dividends	(41,534)					(41,534)
Dividends paid to noncontrolling interests	(214)						(214)
Issuance of stock awards	399			399
Issuance of stock awards (shares)			340,000
Shares repurchased	$ (7,395)			(7,395)
Shares repurchased (shares)	0		(133,000)
Stock-based compensation	$ 4,560			4,560
Ending Balance at Mar. 31, 2019	$ 1,801,139		$ 7,175	$ 302,273	$ (734,745)	$ 2,213,473	$ 12,963
Ending balance (shares) at Mar. 31, 2019	100,036,000		100,036,000

[1] The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.