Accumulated Other Comprehensive Loss - Net Change and Ending Balances for Various Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 67,239	$ 115,893	$ 71,571	$ 112,649
Net change	(595)	(1,511)	(3,067)	121
Ending Balance	69,459	115,580	69,459	115,580
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(23,161)	(26,170)
Net change			(2,722)	1,037
Ending Balance	(25,883)	(25,133)	(25,883)	(25,133)
Unrecognized Employee Benefit Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(40,490)	(32,623)
Net change			(288)	(629)
Ending Balance	(40,778)	(33,252)	(40,778)	(33,252)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			186	152
Net change			(57)	(287)
Ending Balance	129	(135)	129	(135)
Less: Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(476)	(229)
Net change			(273)	(478)
Ending Balance	(749)	(707)	(749)	(707)
Accumulated Other Comprehensive Loss Attributable to Ampco-Pittsburgh [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(62,989)	(58,412)
Net change			(2,794)	599
Ending Balance	(65,783)	(57,813)	(65,783)	(57,813)
Total Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(63,465)	(58,641)
Net change			(3,067)	121
Ending Balance	$ (66,532)	$ (58,520)	$ (66,532)	$ (58,520)