Quarterly report pursuant to Section 13 or 15(d)

Credit Facilities (Details Textual)

v3.20.1
Credit Facilities (Details Textual)
₩ in Thousands
3 Months Ended
Mar. 28, 2020
USD ($)
Mar. 30, 2019
USD ($)
Mar. 28, 2020
KRW (₩)
Debt Instrument [Line Items]      
Loans maturity, description Various    
PNC Bank, National Association, as Administrative Agent, and Lender Party [Member]      
Debt Instrument [Line Items]      
Interest expense recognized $ 2,408,000 $ 4,164,000  
PNC Bank, National Association, as Administrative Agent, and Lender Party [Member] | Revolving Credit Facility [Member]      
Debt Instrument [Line Items]      
Credit facilities, maximum capacity $ 400,000,000    
Effective interest rate 2.34%   2.34%
Shinhan Bank [Member] | Term Loan [Member]      
Debt Instrument [Line Items]      
Credit facilities, maximum capacity | ₩     ₩ 1,000,000
Loan maturity month and year 2020-03    
National Australia Bank [Member] | Other Long-Term Debt [Member]      
Debt Instrument [Line Items]      
Loans, frequency of payments monthly    
Loans maturity, description The loans mature at various dates through July 2023.    
National Australia Bank [Member] | Minimum [Member] | Other Long-Term Debt [Member]      
Debt Instrument [Line Items]      
Interest rates 4.50%   4.50%
National Australia Bank [Member] | Maximum [Member] | Other Long-Term Debt [Member]      
Debt Instrument [Line Items]      
Interest rates 5.10%   5.10%