CONSOLIDATED STATEMENT OF EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Balance at Dec. 31, 2016	$ 1,117,500	$ 18,400	$ 260,400	$ (46,100)	$ 1,071,600	$ (186,800)
Balance (in shares) at Dec. 31, 2016		73,700,000		600,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	150,700				150,700
Shares issued under stock plans (in shares)		1,500,000		(100,000)
Activity related to stock-based compensation	55,900	$ 400	44,100	$ 11,400
Shares purchased under share repurchase program (in shares)				800,000
Shares purchased under share repurchase program	(74,400)			$ (74,400)
Dividends declared	$ (40,000)				(40,000)
Dividends declared per share (in dollars per share)	$ 0.54
Other adjustments to capital in excess of par value	$ 4,800		4,800
Other comprehensive income (loss), net of tax	69,500					69,500
Balance (in shares) at Dec. 31, 2017		75,200,000		1,300,000
Balance at Dec. 31, 2017	1,279,900	$ 18,800	309,300	$ (109,100)	1,178,200	(117,300)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of modified retrospective application of new accounting standard	(4,100)				(4,100)
Net income	206,900				206,900
Shares issued under stock plans (in shares)		100,000		(900,000)
Activity related to stock-based compensation	48,900	$ 0	(27,300)	$ 76,200
Shares purchased under share repurchase program (in shares)				800,000
Shares purchased under share repurchase program	(70,800)			$ (70,800)
Dividends declared	$ (43,100)				(43,100)
Dividends declared per share (in dollars per share)	$ 0.58
Other comprehensive income (loss), net of tax	$ (36,900)					(36,900)
Balance (in shares) at Dec. 31, 2018		75,300,000		1,200,000
Balance at Dec. 31, 2018	1,396,300	$ 18,800	282,000	$ (103,700)	1,353,400	(154,200)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of modified retrospective application of new accounting standard	11,400				11,400
Net income	241,700				241,700
Shares issued under stock plans (in shares)				(800,000)
Activity related to stock-based compensation	$ 54,500	$ 0	(11,100)	$ 65,600
Shares purchased under share repurchase program (in shares)	800,000			800,000
Shares purchased under share repurchase program	$ (83,100)			$ (83,100)
Shares repurchased for employee tax withholdings (in shares)		0
Purchase of investment in affiliated companies	4,900		1,800	$ 3,100
Dividends declared	$ (45,700)				(45,700)
Dividends declared per share (in dollars per share)	$ 0.62
Other comprehensive income (loss), net of tax	$ 4,600					4,600
Balance (in shares) at Dec. 31, 2019		75,300,000		1,200,000
Balance at Dec. 31, 2019	$ 1,573,200	$ 18,800	$ 272,700	$ (118,100)	$ 1,549,400	$ (149,600)