v3.26.1
Accumulated Other Comprehensive Loss - Net Change and Ending Balances for Various Components of Accumulated Other Comprehensive Loss (Detail) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance $ 47,963 $ 71,091
Net change (529) 4,382
Ending Balance 47,576 77,670
Foreign Currency Translation [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance 863 (27,691)
Net change (563) 4,125
Ending Balance 300 (23,566)
Unrecognized Employee Benefit Costs [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (29,405) (39,856)
Net change (61) (464)
Ending Balance (29,466) (40,320)
Cash Flow Hedges [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance 116 (102)
Net change 95 721
Ending Balance 211 619
Less: Noncontrolling Interest [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (222) (813)
Net change 211 71
Ending Balance (11) (742)
Accumulated Other Comprehensive Loss Attributable to Ampco-Pittsburgh [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (28,204) (66,836)
Net change (740) 4,311
Ending Balance (28,944) (62,525)
Total Accumulated Other Comprehensive Loss [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (28,426) (67,649)
Net change (529) 4,382
Ending Balance $ (28,955) $ (63,267)