Significant Accounting Policies - Revenues and Expenses Associated with Servicing of Agreements (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2013
Segment Reporting Information [Line Items]
Material, labor and other production costs	$ 882,337us-gaap_CostOfGoodsAndServicesSold	$ 857,227us-gaap_CostOfGoodsAndServicesSold	$ 817,740us-gaap_CostOfGoodsAndServicesSold
Selling, distribution and marketing expenses	696,543us-gaap_SellingAndMarketingExpense	685,088us-gaap_SellingAndMarketingExpense	653,935us-gaap_SellingAndMarketingExpense
Administrative and general expenses	289,433us-gaap_GeneralAndAdministrativeExpense	297,443us-gaap_GeneralAndAdministrativeExpense	298,569us-gaap_GeneralAndAdministrativeExpense
AG Intellectual Properties [Member] \| Non-Reportable Segment [Member]
Segment Reporting Information [Line Items]
Royalty revenue	22,660	26,170	24,740
Material, labor and other production costs	2,602	8,583	9,929
Selling, distribution and marketing expenses	6,297	6,339	7,336
Administrative and general expenses	2,003	1,945	1,848
Expenses associated with royalty revenue, Total	$ 10,902	$ 16,867	$ 19,113

Total expenses associated with royalty revenue.

No definition available.

Name:	am_ExpensesAssociatedWithRoyaltyRevenue
Namespace Prefix:	am_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 2

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2(a),(d))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

+ Details

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

- Definition

Revenue earned during the period from the leasing or otherwise lending to a third party the entity's rights or title to certain property. Royalty revenue is derived from a percentage or stated amount of sales proceeds or revenue generated by the third party using the entity's property. Examples of property from which royalties may be derived include patents and oil and mineral rights.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

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

- Details

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

- Definition

The aggregate total amount of expenses directly related to the marketing or selling of products or services.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_ProductOrServiceAxis=am_AgIntellectualPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: