CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - 6 months ended Jun. 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	22,326	0	0	22,326
Other comprehensive income (loss), net of tax	0	0	0	(1,334)	0	(1,334)
Cash dividends paid	0	0	(6,876)	0	0	(6,876)
Purchase of treasury stock	0	0	0	0	(7,046)	(7,046)
Stock-based compensation and related tax benefits	0	1,809	0	0	1,169	2,978
Stock options exercised and related tax benefits	0	(19)	0	0	207	188
Employee Stock Ownership Plan	0	1,001	0	0	1,207	2,208
Balance at Jun. 30, 2015	$ 47,872	$ 94,202	$ 274,610	$ (3,986)	$ (26,101)	$ 386,597