Number of defined contribution plans sponsored by the employer as of the end of the reporting period.

No definition available.

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Namespace Prefix:	am_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

+ Details

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Balance Type:	debit
Period Type:	duration

- Details

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Period Type:	duration

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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Retirement and Postretirement Benefit Plans (Defined Contribution Plan) - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2013
Profit-Sharing Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer's contributions to a defined contribution retirement plan	$ 9,180	$ 9,149	$ 7,536
United States [Member] \| 401 (k) [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer's contributions to a defined contribution retirement plan	4,575	5,070	6,273
United Kingdom [Member] \| Defined Contribution Plans [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer's contributions to a defined contribution retirement plan	2,558	2,124	1,970
Canadian Subsidiary [Member]
Defined Contribution Plan Disclosure [Line Items]
Number of defined contribution plan	1
Employer's contributions to a defined contribution retirement plan	$ 354	$ 378	$ 359
Canadian Subsidiary [Member] \| Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employee contribution, matching percentage of eligible compensation	2.00%
Canadian Subsidiary [Member] \| Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employee contribution, matching percentage of eligible compensation	4.00%