Fair Value of Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Apr. 30, 2014
Debt Disclosure [Abstract]
The total carrying value of short-term borrowings and long-term debt	$ 1,079.2	$ 991.8
Total fair value of short-term borrowings and long-term debt	$ 1,100.0us-gaap_DebtInstrumentFairValue	$ 1,100.0us-gaap_DebtInstrumentFairValue

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant