| Quarterly Financial Information [Table Text Block] | 
 
		
			
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						Fiscal 2018 
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						(in thousands, except per share data) 
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						First Quarter 
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						Second Quarter 
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						Third Quarter 
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						Fourth Quarter 
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						Net sales 
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						$ 
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						 402,948 
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						$ 
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						 434,279 
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						$ 
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						 435,882 
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						$ 
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						 436,739 
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						Gross profit 
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						 165,386 
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						 177,638 
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						 178,226 
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						 181,018 
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						Income from continuing operations 
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						 36,506 
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						 37,245 
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						 34,237 
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						 23,313 
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						Basic earnings from continuing operations per share 
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						 0.38 
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						 0.39 
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						 0.35 
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						 0.24 
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				| 
					 
						Diluted earnings from continuing operations per share 
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						 0.35 
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						 0.35 
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						 0.33 
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						 0.22 
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				| 
					 
						Net income 
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						 31,871 
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						 39,846 
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						 26,568 
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						 17,902 
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						Basic earnings per share 
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						 0.33 
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						 0.41 
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						 0.27 
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						 0.18 
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						Diluted earnings per share 
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						 0.30 
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						 0.38 
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						 0.25 
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						 0.17 
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						Fiscal 2017 
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						(in thousands, except per share data) 
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						First Quarter 
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						Second Quarter 
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						Third Quarter 
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						Fourth Quarter 
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						Net sales 
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						$ 
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						 307,296 
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						$ 
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						 344,047 
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						$ 
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						 343,923 
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						$ 
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						 389,501 
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						Gross profit 
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						 125,471 
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						 142,228 
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						 142,491 
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						 162,374 
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						Income from continuing operations 
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						 22,672 
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						 34,102 
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						 28,596 
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						 32,401 
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						Basic earnings from continuing operations per share 
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				 | 
				
					 
						  
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						 0.27 
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						 0.38 
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						 0.30 
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						 0.34 
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						Diluted earnings from continuing operations per share 
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				 | 
				
					 
						  
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						 0.26 
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						 0.34 
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						 0.28 
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						 0.31 
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						Net income 
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						 11,128 
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						 20,429 
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						 23,255 
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						 47,976 
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						Basic earnings per share 
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						 0.13 
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						 0.22 
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						 0.25 
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						 0.51 
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						Diluted earnings per share 
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				 | 
				
					 
						  
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						 0.13 
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						 0.20 
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						 0.22 
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						 0.46 
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