Income Taxes - Reconciliation of Taxes Reported At Company's Tax Rate And U.S. Federal Statutory Tax Rate (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Income Taxes      
Tax at statutory rates $ 3,705 $ (159) $ 3,255
Foreign rate differential 2,095 558 1,969
GILTI Inclusion   (886) 2,173
Changes in deferred tax assets (1,189) 3,919 277
Mexico mining tax 1,590 280 1,126
Foreign exchange 535 866 255
Stock option expiration 2,471 449 361
Mexico Withholding Tax 679 192 374
Deduction for Inflation in Mexico (981) (550) (338)
U.S. State income tax 585 127 139
Other 125 777 376
Total income tax provision $ 9,615 $ 5,573 $ 9,967