Equity method investment other than temporary impairment per share.

No definition available.

Name:	ap_EquityMethodInvestmentOtherThanTemporaryImpairmentPerShare
Namespace Prefix:	ap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated additional insurance recoveries included in earning after tax credit.

+ References

No definition available.

+ Details

Name:	ap_EstimatedAdditionalInsuranceRecoveriesIncludedInEarningAfterTaxCredit
Namespace Prefix:	ap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Estimated additional insurance recoveries included in earning after tax credit per share.

+ References

No definition available.

+ Details

Name:	ap_EstimatedAdditionalInsuranceRecoveriesIncludedInEarningAfterTaxCreditPerShare
Namespace Prefix:	ap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 35

-Paragraph 32

-URI http://asc.fasb.org/extlink&oid=35687916&loc=d3e32787-111569

+ Details

Name:	us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after tax, before reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i-k)

-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669646-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeReclassificationAdjustmentsNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Quarterly Information - Quarterly Information - Unaudited (Parenthetical) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
After-tax credit				$ 10,621
After-tax credit per common share for the estimated additional insurance recoveries				$ 1.03
After-tax charge	2,916		4,165
After-tax charge per common share to recognize	$ 0.28		$ 0.40
Unrecognized employee benefit costs	$ (27,252)	$ 4,776	$ 29,080		$ (21,392)	$ 28,678	$ (10,520)