Anticipated year of construction completion and when the building will be ready for occupancy.

No definition available.

Name:	am_ConstructionCompletionYear
Namespace Prefix:	am_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross amount of capitalized construction in progress costs having an offsetting recorded deferred lease obligation.

+ References

No definition available.

+ Details

Name:	am_DeemedOwnerAssetAndLiability
Namespace Prefix:	am_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cost per acre for acquisition of land for use.

+ References

No definition available.

+ Details

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Namespace Prefix:	am_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Unconsolidated related party's equity interest in a service provider, lessor or supplier to the entity.

+ References

No definition available.

+ Details

Name:	am_RelatedPartyOwnershipPercentage
Namespace Prefix:	am_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of land held.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of the lessee's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 825

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6480020&loc=d3e61082-112788

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 825

-Section 50

-Paragraph 1

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=6480020&loc=d3e61044-112788

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay, due within 1 year (or 1 business cycle).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(k)(1))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph a

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph k

-Subparagraph 1

-Article 4

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Related Parties

-URI http://asc.fasb.org/extlink&oid=16382449

+ Details

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

- Definition

This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 3)

-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 25

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=7661868&loc=d3e34039-112682

+ Details

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

- Definition

The cash outflow for acquisition of land for use; excludes purchases of land held as inventory or as investments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

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

- Details

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

- Details

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Namespace Prefix:
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Related Party Information (World headquarters relocation) - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			0 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2013	Mar. 26, 2014
Related Party Transaction [Line Items]
Expected annual lease rent	$ 84,612	$ 83,790	$ 66,840
WHQ Development [Member]
Related Party Transaction [Line Items]
Purchase price of land				7,390
Area of land purchased				14.48
Purchase price of land per acre				510
Equity interest held by unconsolidated related party in development project owner				37.00%
Anticipated year of completion for new world headquarters building	2016
Initial lease term	15 years
Expected annual lease rent	9,500
Deferred lease obligation related to assets and corresponding liabilities	31,662
WHQ Development [Member] \| Construction Loan [Member]
Related Party Transaction [Line Items]
Loan agreement, maximum amount to fund costs	9,000
Loan agreement, current amount outstanding	$ 0