Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 432,401	$ 331,866	$ 238,480
Operating costs and expenses:
Costs of products sold (excluding depreciation and amortization)	357,672	276,496	196,091
Selling and administrative	61,310	58,175	39,510
Depreciation and amortization	22,387	20,463	11,787
Charge (credit) for asbestos litigation	0	4,565	(14,333)
Charges for impairment	0	26,676	0
Loss on disposition of assets	401	21	378
Total operating expenses	441,770	386,396	233,433
(Loss) income from operations	(9,369)	(54,530)	5,047
Other income (expense):
Investment-related income	133	481	174
Interest expense	(3,525)	(2,397)	(226)
Other – net	(932)	(1,074)	(475)
Total other income (expense)	(4,324)	(2,990)	(527)
(Loss) income before income taxes and equity gains (losses) in joint venture	(13,693)	(57,520)	4,520
Income tax benefit (provision)	1,355	(22,712)	(2,633)
Equity gains (losses) in joint venture, including gain on sale (Note 3)	1,036	423	(514)
Net (loss) income	(11,302)	(79,809)	1,373
Less: Net income attributable to noncontrolling interest	787	11	0
Net (loss) income attributable to Ampco-Pittsburgh	$ (12,089)	$ (79,820)	$ 1,373
Net (loss) income per common share attributable to Ampco-Pittsburgh:
Basic	$ (0.98)	$ (6.68)	$ 0.13
Diluted	$ (0.98)	$ (6.68)	$ 0.13
Weighted average number of common shares outstanding:
Basic	12,330,000	11,951,000	10,435,000
Diluted	12,330,401	11,951,181	10,447,066