Guarantor and Non-Guarantor Financial Information (Details Textual) (3.50% Senior Notes due October 15, 2021 [Member])	Jan. 31, 2015	Apr. 30, 2014
3.50% Senior Notes due October 15, 2021 [Member]
Guarantor and Non Guarantor Financial Information (Textual) [Abstract]
Interest rate on notes	3.50%	3.50%
Percentage ownership of wholly-owned subsidiaries	100.00%

Contractual interest rate for funds borrowed, under the debt agreement.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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