Annual report pursuant to Section 13 and 15(d)

Derivative Financial Instruments (Narrative) (Details)

v3.20.4
Derivative Financial Instruments (Narrative) (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Sales $ 75,947 $ 64,491 $ 30,014 $ 53,555 $ 61,022 $ 60,203 $ 46,994 $ 61,218 $ 224,007 $ 229,437 $ 212,141
Unrealized Gains (Losses) on Cash Flow Hedges [Member]                      
Maximum net exposure to counterparty                 1,629    
Reclassification Out Of Accumulated Other Comprehensive Income [Member]                      
Sales                 $ (139) $ 1,017