Annual report pursuant to Section 13 and 15(d)

Summary Of Significant Accounting Policies (Narrative) (Details)

v3.10.0.1
Summary Of Significant Accounting Policies (Narrative) (Details)
shares in Thousands
 3 Months Ended 12 Months Ended
Jun. 30, 2018
USD ($)
Dec. 29, 2018
USD ($)
item
shares
Dec. 30, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Summary Of Significant Accounting Policies [Line Items]        
Geographical regions | item   2    
Sub-geographical regions | item   3    
Transfers of financial assets or liabilities   $ 0 $ 0  
Non-financial assets   0 0 $ 0
Receivable from credit card processors   11,860,000 11,517,000  
Impairment     2,734,000  
Other-than-temporary impairments   $ 0    
Maturity date   Feb. 01, 2024    
Notes receivable     6,734,000  
Credits on notes receivable     86,000 1,288,000
Goodwill impairment   $ 0 0 0
Impairment of indefinite-lived intangible assets   0 0 0
Amount of individual claims before reimbursement   150,000    
Minimum amount of aggregate claims before reimbursement   10,464,000    
Self insurance program expense   10,869,000 $ 9,195,000 $ 9,015,000
Amount available to repurchase under the stock repurchase plan   $ 70,216,000    
Common stock repurchased and retired, shares | shares   900 865 1,106
Repurchase of common stock   $ 105,375,000 $ 50,000,000 $ 64,610,000
Duration of product return for first order   30 days    
Percentage of sale refunded   100.00%    
Duration of product return   1 year    
Amount of returned product which could result in cancellation of distributorship   $ 100    
Product return percentage of net sales   0.70% 0.70% 0.70%
Advertising expense   $ 10,345,000 $ 11,503,000 $ 12,266,000
Research and development expense   10,242,000 8,952,000 8,842,000
Derivative outstanding   0 0  
Notional amount $ 105,000,000      
Derivative gain $ 739,000      
Loans recovered   4,800,000    
Contract assets   0    
Restricted cash   2,908,000 3,076,000 $ 2,880,000
Penalty   0    
Accounting Standards Update 2016-02 [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Operating, right-of-use   $ 7,000,000    
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]   us-gaap:Assets    
Manufacturing Credits [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Credits on notes receivable   $ 0 $ 420,000  
Minimum [Member] | Accounting Standards Update 2016-02 [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Impact of adopting ASU   18,000,000    
Maximum [Member] | Accounting Standards Update 2016-02 [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Impact of adopting ASU   $ 25,000,000    
LIBOR [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Basis point   4.00%