Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	48 Months Ended
Jul. 31, 2014	Jul. 31, 2013	Apr. 30, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	29.20%	37.70%
Federal research and experimentation tax credit			$ 1.1

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 2

-Article 4

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