CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF EARNINGS [Abstract]
Revenue	$ 1,332,001	$ 1,322,934	$ 1,386,815
Cost of products sold	908,254	908,061	920,686
Selling and administrative expenses	271,091	293,763	262,751
Operating income	152,656	121,110	203,378
Interest expense	14,811	20,107	21,853
Earnings before income taxes	137,845	101,003	181,525
Income taxes	28,373	18,956	24,165
Net earnings	$ 109,472	$ 82,047	$ 157,360
Earnings per common share:
Basic (in dollars per share)	$ 2.59	$ 1.94	$ 3.71
Diluted (in dollars per share)	$ 2.59	$ 1.94	$ 3.70
Weighted average number of common shares outstanding:
Basic (in shares)	42,301	42,263	42,404
Diluted (in shares)	42,346	42,294	42,499