Annual report pursuant to Section 13 and 15(d)

Item 15 (Details)

v3.20.4
Item 15 (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]        
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]        
Allowances for Doubtful Accounts $ 0 $ 0 $ 46 $ 73
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense 0 0 0  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account 0 0 0  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction 0 (46) (27)  
SEC Schedule, 12-09, Reserve, Warranty [Member]        
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]        
Allowances for Doubtful Accounts 700 553 519 941
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense 300 74 (414)  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account 0 0 0  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction (153) (40) (8)  
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]        
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]        
Allowances for Doubtful Accounts 71,811 77,957 79,196 $ 84,560
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense (7,385) (1,239) (5,761)  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account 1,239 0 397  
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction $ 0 $ 0 $ 0