CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2014	$ 47,872	$ 91,411	$ 259,160	$ (2,652)	$ (21,638)	$ 374,153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	0	0	40,792	0	0	40,792
Other comprehensive income (loss), net of tax	0	0	0	(3,203)	0	(3,203)
Cash dividends paid	0	0	(10,299)	0	0	(10,299)
Purchase of treasury stock	0	0	0	0	(15,519)	(15,519)
Stock-based compensation and related tax benefits	0	2,739	0	0	1,278	4,017
Stock options exercised and related tax benefits	0	2	0	0	207	209
Employee Stock Ownership Plan	0	1,001	0	0	1,207	2,208
Balance at Sep. 30, 2015	$ 47,872	$ 95,153	$ 289,653	$ (5,855)	$ (34,465)	$ 392,358