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Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Nov. 28, 2014
Nov. 29, 2013
Nov. 28, 2014
Nov. 29, 2013
Income Taxes [Line Items]        
Income tax expense benefit computation description     The Corporation's provision for income taxes in interim periods is computed by applying its estimated annual effective tax rate against income before income tax expense for the period. In addition, non-recurring or discrete items are recorded during the period in which they occur.  
Effective tax rate 35.70%us-gaap_EffectiveIncomeTaxRateContinuingOperations 8.60%us-gaap_EffectiveIncomeTaxRateContinuingOperations 27.60%us-gaap_EffectiveIncomeTaxRateContinuingOperations 49.10%us-gaap_EffectiveIncomeTaxRateContinuingOperations
Federal tax refund     $ 4.1am_IncomeTaxReconciliationAccrualsAndSettlements  
Adjustment to valuation allowance attributable to certain net operating loss and foreign tax credit carryforwards       8.0us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Unrecognized tax benefits 21.6us-gaap_UnrecognizedTaxBenefits   21.6us-gaap_UnrecognizedTaxBenefits  
Income tax expenses affected by unrecognized tax benefits if recognized 19.1us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate   19.1us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate  
Unrecognized tax benefits increased     2.6us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease  
Decrease in unrecognized tax benefits 3.0us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit   3.0us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit  
Unrecognized tax benefits income tax penalties and interest accrued description     The Corporation recognizes interest and penalties accrued on unrecognized tax benefits and refundable income taxes as a component of income tax expense.  
Interest and penalties on unrecognized tax benefits and refundable income taxes     3.8us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense  
Accrued Interest and penalties on unrecognized tax benefit 0.6us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued   0.6us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued  
Open tax years by major tax jurisdiction     The Corporation is subject to examination by the IRS for tax years 2010 to the present and various U.S. state and local jurisdictions for tax years 2001 to the present. The Corporation is also subject to tax examination in various international tax jurisdictions, including Canada, the United Kingdom, Australia, Italy, Mexico and New Zealand for tax years 2006 to the present.  
Adjustments for Error Correction [Member]        
Income Taxes [Line Items]        
Reduction in income tax expense     $ 4.1us-gaap_IncreaseDecreaseInDeferredIncomeTaxes
/ us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis
= am_AdjustmentsForErrorCorrectionMember