Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 1,224	$ 861	$ 1,538	$ 5,463
Adjustments for changes in:
Foreign currency translation	1,314	2,924	458	(1,958)
Unrecognized employee benefit costs (including effects of foreign currency translation)	(85)	(95)	(28)	598
Fair value of cash flow hedges	245	378	555	(200)
Reclassification adjustments for items included in net income:
Amortization of unrecognized employee benefit costs	552	378	914	763
Settlements of cash flow hedges	(389)	172	(720)	157
Other comprehensive income (loss)	1,637	3,757	1,179	(640)
Comprehensive income	2,861	4,618	2,717	4,823
Less: Comprehensive income attributable to noncontrolling interest	229	215	410	553
Comprehensive income attributable to Ampco-Pittsburgh	$ 2,632	$ 4,403	$ 2,307	$ 4,270