CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2017		46,871				1,704
Beginning Balance at Dec. 31, 2017	$ 2,430,531	$ 46,871	$ 591,721	$ 2,285,886	$ (265,091)	$ (228,856)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	56,184			56,184
Cash dividends ($0.34 per share)	(15,447)			(15,447)
Other comprehensive (loss) income	82,690				82,690
Shares issued under compensation plans (in shares)		(97)				(43)
Shares issued under compensation plans	4,122	$ 97	992			$ 3,033
Deferred compensation (in shares)						(8)
Deferred compensation	322					$ 322
Settlements of note hedges associated with convertible notes	(12)		(17,884)			$ 17,872
Settlements of note hedges associated with convertible notes (in shares)						(132)
Ending Balance (in shares) at Apr. 01, 2018		46,968				1,521
Ending Balance at Apr. 01, 2018	2,560,500	$ 46,968	574,829	2,328,733	(182,401)	$ (207,629)
Beginning Balance (in shares) at Dec. 31, 2018		47,248				1,232
Beginning Balance at Dec. 31, 2018	2,539,978	$ 47,248	574,761	2,427,599	(341,085)	$ (168,545)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,897			40,897
Cash dividends ($0.34 per share)	(15,650)			(15,650)
Other comprehensive (loss) income	396				396
Shares issued under compensation plans (in shares)		(75)				(40)
Shares issued under compensation plans	5,198	$ 75	$ 3,094			$ 2,029
Deferred compensation (in shares)			(127)			(4)
Deferred compensation	380					$ 253
Ending Balance (in shares) at Mar. 31, 2019		47,323				1,188
Ending Balance at Mar. 31, 2019	$ 2,569,878	$ 47,323	$ 577,982	$ 2,451,525	$ (340,689)	$ (166,263)