CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Unaudited) - 9 months ended Sep. 30, 2017 - USD ($) shares in Thousands, $ in Thousands	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2016	$ 21,749		$ 803,152	$ (18,102)	$ 806,799
Balance (in shares) at Dec. 31, 2016	217,489
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for stock incentive plans, net	$ 46	$ 8,973			9,019
Stock issued for stock incentive plans, net (in shares)	459
Stock purchased and retired	$ (137)	$ (8,973)	(17,614)		(26,724)
Stock purchased and retired (in shares)	(1,363)
Net income			104,808		104,808
Dividends			(13,026)		(13,026)
Pension adjustment, net of taxes				405	405
Foreign currency translation				584	584
Unrealized loss on securities, net of taxes				(12)	(12)
Balance at Sep. 30, 2017	$ 21,658		$ 877,320	$ (17,125)	$ 881,853
Balance (in shares) at Sep. 30, 2017	216,585