Number of derivative instruments holds for trading purposes.

No definition available.

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- Definition

Number of subsidiaries who have committed to purchase a portion of their anticipated natural gas requirements in advance.

+ References

No definition available.

+ Details

Name:	ap_NumberOfSubsidiariesPurchasedCommitmentsForNaturalGasUsage
Namespace Prefix:	ap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of anticipated requirements which are covered by cash flow hedges.

+ References

No definition available.

+ Details

Name:	ap_PercentageOfAnticipatedPurchasesHedged
Namespace Prefix:	ap_
Data Type:	num:percentItemType
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Period Type:	instant

- Definition

Percentage of anticipated requirements which are covered by purchase commitments.

+ References

No definition available.

+ Details

Name:	ap_PercentageOfPurchaseCommitmentsCoveringAnticipatedNaturalGasUsageApproximate
Namespace Prefix:	ap_
Data Type:	num:percentItemType
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Period Type:	instant

- Definition

Period covered by cash flow hedges.

+ References

No definition available.

+ Details

Name:	ap_PeriodForHedgedPurchases
Namespace Prefix:	ap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Dollar value of anticipated natural gas requirements which are covered by purchase commitments.

+ References

No definition available.

+ Details

Name:	ap_PurchaseCommitmentAmountOfAnticipatedNaturalGasUsage
Namespace Prefix:	ap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Purchase commitments covering period anticipated usage description.

+ References

No definition available.

+ Details

Name:	ap_PurchaseCommitmentsCoveringPeriodAnticipatedUsageDescription
Namespace Prefix:	ap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of hedged item in hedging relationship. Excludes hedged asset or liability.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30700-110894

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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- Details

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Derivative Instruments - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) Customer Derivative	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Customer Derivative	Jun. 30, 2017 USD ($)
Derivative [Line Items]
Anticipated foreign-denominated sales hedge	$ 20,519,000		$ 20,519,000
Percentage of purchase commitments covering anticipated natural gas usage	47.00%		47.00%
Purchase commitment amount of anticipated natural gas usage	$ 467,000		$ 467,000
Number of subsidiaries purchased commitments for natural gas usage \| Customer	1		1
Purchase commitments covering period anticipated usage, Description			for one of its subsidiaries.
Number of derivative instruments holds for trading purposes \| Derivative	0		0
(Losses) gains on foreign exchange transactions included in other income (expense)	$ (881,000)	$ 361,000	$ (1,702,000)	$ (703,000)
Natural Gas Purchases [Member]
Derivative [Line Items]
Purchase of natural gas	$ 396,000	$ 0	$ 818,000	$ 0
Copper Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	46.00%		46.00%
Time period for hedged purchases			11 months
Copper Purchases [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 2,504,000		$ 2,504,000
Aluminum Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	56.00%		56.00%
Time period for hedged purchases			6 months
Aluminum Purchases [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 557,000		$ 557,000