Consolidated Statement Of Equity - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Common Stock [Member]	Capital In Excess Of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Total
Balance at Dec. 31, 2015	$ 89,682	$ 773,585	$ 930,061	$ (68,085)	$ 687	$ 1,725,930
Net income			184,533			184,533
Other comprehensive loss, net of income tax benefit of $16					(31)	(31)
Dividends			(96,994)			(96,994)
Stock issued for acquisition (439,943 shares)	220	12,625				12,845
Sale of stock (34,699 shares)	17	1,012				1,029
Repurchase of stock (93,369 shares)				(2,905)		(2,905)
Equity compensation plan (225,712 shares)	113	(113)
Exercise of stock options (204,014 shares)	102	3,734				3,836
Stock-based compensation		3,642	(339)			3,303
Employee stock plan tax benefits		1,263				1,263
Other		(609)				(609)
Balance at Sep. 30, 2016	$ 90,134	$ 795,139	$ 1,017,261	$ (70,990)	$ 656	$ 1,832,200