Business Segment Information (Termination Benefits) - Additional Information (Detail) - USD ($) $ in Millions	Nov. 27, 2015	Feb. 28, 2015	Nov. 28, 2014
Segment Reporting [Abstract]
Severance accrual	$ 3.1	$ 4.3	$ 4.5

Liabilities associated with termination benefits accounted for in accordance with ASC Topic 712, Compensation - Nonretirement Postemployment Benefits; includes current and noncurrent portions.

No definition available.

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