Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (19,560)	$ (67,476)
Adjustments for changes in:
Foreign currency translation	290	(6,710)
Unrecognized employee benefit costs (including effects of foreign currency translation)	(19,655)	3,205
Fair value of cash flow hedges	97	(713)
Reclassification adjustments for items included in net loss:
Amortization of unrecognized employee benefit costs	(302)	89
Realized losses (gains) from settlement of cash flow hedges	258	(90)
Other comprehensive loss	(19,312)	(4,219)
Comprehensive loss	(38,872)	(71,695)
Less: Comprehensive income attributable to noncontrolling interest	1,342	1,682
Comprehensive loss attributable to Ampco-Pittsburgh	$ (40,214)	$ (73,377)

Other comprehensive income loss gross adjustments net of tax.

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