Accumulated Other Comprehensive Loss - Net Changes and Ending Balances for Various Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 71,571	$ 112,649
Net change	(4,184)	(4,824)
Ending Balance	71,091	71,571
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(23,161)	(26,170)
Net change	(4,530)	3,009
Ending Balance	(27,691)	(23,161)
Unrecognized Components of Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(40,490)	(32,623)
Net change	634	(7,867)
Ending Balance	(39,856)	(40,490)
Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	186	152
Net change	(288)	34
Ending Balance	(102)	186
Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(476)	(229)
Net change	(337)	(247)
Ending Balance	(813)	(476)
Accumulated Other Comprehensive Loss Attributable to Ampco-Pittsburgh [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(62,989)	(58,412)
Net change	(3,847)	(4,577)
Ending Balance	(66,836)	(62,989)
Total Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(63,465)	(58,641)
Net change	(4,184)	(4,824)
Ending Balance	$ (67,649)	$ (63,465)