Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 112,216	$ 103,886	$ 354,720	$ 317,952
Operating costs and expenses:
Costs of products sold (excluding depreciation and amortization)	98,408	87,346	301,741	264,179
Selling and administrative	14,512	14,218	44,799	44,648
Depreciation and amortization	5,683	5,451	17,357	17,019
Loss on disposal of assets	298	110	237	109
Total operating expenses	118,901	107,125	364,134	325,955
Loss from operations	(6,685)	(3,239)	(9,414)	(8,003)
Other income (expense):
Investment-related income	440	34	507	105
Interest expense	(1,082)	(778)	(2,975)	(2,683)
Other – net	1,671	276	5,022	(39)
Total other income (expense)	1,029	(468)	2,554	(2,617)
Loss before income taxes and equity income in joint venture	(5,656)	(3,707)	(6,860)	(10,620)
Income tax (provision) benefit	(800)	1,804	(907)	1,771
Equity income in joint venture	0	0	0	535
Net loss	(6,456)	(1,903)	(7,767)	(8,314)
Less: Net income attributable to noncontrolling interest	583	299	1,325	584
Net loss attributable to Ampco-Pittsburgh shareholders	$ (7,039)	$ (2,202)	$ (9,092)	$ (8,898)
Net loss per common share attributable to Ampco-Pittsburgh:
Basic	$ (0.56)	$ (0.18)	$ (0.73)	$ (0.72)
Diluted	(0.56)	(0.18)	(0.73)	(0.72)
Cash dividends declared per share	$ 0.00	$ 0.00	$ 0.00	$ 0.09
Weighted average number of common shares outstanding:
Basic	12,494	12,361	12,432	12,320
Diluted	12,494	12,361	12,432	12,320