Pensions and Other Postretirement Benefits (Details Textual)	6 Months Ended
Oct. 31, 2011 Position
Pensions and Other Postretirement Benefits (Textual) [Abstract]
Reduction in positions due to restructuring	850

The expected number of positions to be eliminated as a result of restructuring activities.

No definition available.

Name:	us-gaap_RestructuringAndRelatedCostExpectedNumberOfPositionsEliminated
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration