Pension Benefits (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Jan. 31, 2016	Apr. 30, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Expected company contributions to pension plan	$ 5.0
Pension contribution	$ 5.0	$ 4.3

The increase in the fair value of plan assets from contributions made by the employer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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